Periodontal disease and gene-expression levels of metalloendopeptidases in human buccal mucosal epithelium.

BACKGROUND AND OBJECTIVE: Endopeptidases, such as neutral endopeptidase (NEP), endothelin-converting enzyme-1 (ECE-1) and a disintegrin and metalloprotease 17 (ADAM17), are believed to have various important roles in oral mucosal and epidermal tissue for the regulation of defensive biological responses in the oral cavity, and their expression and activity are influenced by various factors, including oral diseases. However, knowledge concerning these endopeptidases in the oral cavity has been minimal until now. This study focused on three metalloendopeptidases - NEP, ECE-1 and ADAM17 - in the oral buccal mucosal epithelium of patients with periodontal diseases and investigated the relationship between their gene-expression levels and periodontal disease. MATERIAL AND METHODS: The levels of expression of NEP, ECE-1 and ADAM17 mRNAs in tissue samples collected from the oral buccal mucosal epithelium of 61 patients were investigated by relative quantification using real-time RT-PCR analysis. information on oral and systemic health was obtained from the clinical record of each patient. RESULTS: Among the three groups, classified based on the diagnosis of periodontal diseases (healthy/gingivitis, early periodontitis and moderate/advanced periodontitis), the relative expression level of NEP mRNA was significantly increased in the early periodontitis group and in the moderate/advanced periodontitis group compared with that in the healthy/gingivitis group. Moreover, the relative expression levels of ECE1 and ADAM17 mRNAs were significantly increased in the moderate/advanced periodontitis group compared with those in the healthy/gingivitis group. The correlation coefficients between the mean relative expression levels of NEP and ECE1 mRNAs, NEP and ADAM17 mRNAs, and ECE1 and ADAM17 mRNAs were r = 0.758, r = 0.707 and r = 0.934, respectively (p < 0.001). Furthermore, among the oral-related factors, there was a significant correlation between the number of sites with probing pocket depths of more than 4 mm and of more than 6 mm and the relative expression levels of NEP, ECE1 and ADAM17 mRNAs. In stepwise logistic regression models, high relative expression levels of ECE1 and ADAM17 mRNAs were significantly associated with moderate/advanced periodontitis. CONCLUSION: The present study suggests that the severity of periodontal disease may be associated with the expression of metalloendopeptidase genes, including NEP, ECE1 and ADAM17, in the buccal mucosal epithelium.

Streptococcus anginosus l-cysteine desulfhydrase gene expression is associated with abscess formation in BALB/c mice.

Streptococcus anginosus, an anginosus group bacterium, is frequently isolated from odontogenic abscesses, and is the oral bacterium that is primarily responsible for producing hydrogen sulfide from l-cysteine through the action of its l-cysteine desulfhydrase (ßC-S lyase) enzyme. However, the relationship between its production of hydrogen sulfide and abscess formation has not been investigated. To elucidate the etiological role of hydrogen sulfide in abscess formation, we initially measured, using specific primers, expression of the lcd gene, which encodes ßC-S lyase, in the pus of abscesses that formed in BALB/c mice following subcutaneous injection of S. anginosus into the dorsa. Expression of lcd was >15-fold higher when l-cysteine was present than when it was absent. A mouse virulence assay revealed that the mean diameter of abscesses caused by S. anginosus FW73 plus l-cysteine was greater than that of abscesses caused by S. anginosus FW73 in the absence of l-cysteine. These findings demonstrate that the lcd gene of S. anginosus is upregulated in mouse abscesses and that hydrogen sulfide, the product of a reaction catalyzed by ßC-S lyase, plays an etiological role in odontogenic abscess formation.

Cognitive function and number of teeth in a community-dwelling elderly population without dementia.

Although the number of sound or decayed teeth has been reported to be associated with cognitive function in elderly populations with dementia, little is known about this association in elderly populations without dementia. We evaluated this relationship, with adjustment for confounding factors, in Japanese populations of 60-year-old (n = 270; 120 males and 150 females) and 65-year-old (n = 123; 57 males and 66 females) individuals residing in Fukuoka Prefecture of Japan. Dental examinations were performed in all subjects, along with the Mini-mental state examination (MMSE) for assessing cognitive function. Among the total of 393 subjects, the mean MMSE score was 27.9 +/- 1.9, and 391 subjects scored 24 or higher. The mean numbers of sound and decayed teeth were 12.0 +/- 6.3 and 0.5 +/- 1.2, respectively. Associations were found between the numbers of sound and decayed teeth and MMSE in total subjects and males, but not in females, by multiple regression analysis adjusted for gender, age, level of education, marital status, smoking, alcohol drinking, working status, systolic blood pressure and blood glucose. An association was also found between MMSE and the number of sound teeth in a logistic regression analysis. In conclusion, associations were found between normal-range cognitive function and the numbers of sound and decayed teeth, after adjustment for various confounding factors, in an elderly Japanese population.

Physical fitness and cognitive function in an 85-year-old community-dwelling population.

BACKGROUND: Little is known about the association between physical fitness and cognitive function in very elderly people (over 80 years of age). OBJECTIVES: To evaluate that relationship in 85-year-old community-dwelling individuals. METHODS: Out of 207 participants (90 males, 117 females) who were 85 years old and community-dwelling, 205 completed the Mini-Mental State Examination (MMSE) for evaluating cognitive function. The numbers of subjects who completed physical fitness measurements such as hand-grip strength, isometric leg extensor strength, one-leg standing time, stepping rate, and walking speed were 198, 159, 169, 168, and 151, respectively. RESULTS: There were significant associations in MMSE with hand-grip strength (right or left hand), isometric leg extensor strength, stepping rate, and walking speed by simple regression analysis. MMSE was still significantly associated with hand-grip strength (beta = 0.305, p = 0.005 for right side; beta = 0.309, p = 0.004 for left side), stepping rate (beta = 0.183, p = 0.046), and walking speed (beta = -0.222, p = 0.014) by multiple regression analysis after adjustments for the amount of education, gender, smoking, drinking, complication of stroke, body weight, body height, regular medical care, serum albumin, blood HbA1c, and marital status. By logistic regression analysis, the prevalence of a normal MMSE score (MMSE >or=24) was increased by 9% with each 1-kg increase in hand-grip strength of the left hand (OR 1.087, 95% CI 1.003-1.179, p = 0.042), and was increased by 6% with each step per 10 s in stepping rate (OR 1.060, 95% CI 1.000-1.122, p = 0.048). CONCLUSION: In a very elderly population of 85-year-olds, cognitive function was associated with some physical fitness measurements, independent of confounding factors.

Oral health and mortality risk from pneumonia in the elderly.

Although poor oral health influences the occurrence of pulmonary infection in elderly people, it is unclear how the degree of oral health is linked to mortality from pulmonary infection. Therefore, we evaluated the relationship between oral health and four-year mortality from pneumonia in an elderly Japanese population. The study population consisted of 697 (277 males, 420 females) of the 1282 individuals who were 80 years old in 1997. Data on oral and systemic health were obtained by means of questionnaires, physical examinations, and laboratory blood tests. One hundred eight of the study persons died between 1998 and 2002. Of these, 22 deaths were due to pneumonia. The adjusted mortality due to pneumonia was 3.9 times higher in persons with 10 or more teeth with a probing depth exceeding 4 mm (periodontal pocket) than in those without periodontal pockets. Therefore, the increase in teeth with periodontal pockets in the elderly may be associated with increased mortality from pneumonia.

Number of teeth and serum lipid peroxide in 85-year-olds.

OBJECTIVES: To investigate influence of dental status on systemic oxidative stress, we evaluated the association between number of teeth and serum lipid peroxide, an oxidative stress index, in 85-years old residents of Japan. METHODS: In October 2003, 207 subjects 85-years old agreed to participate in the present follow-up study after five years from the 8020 Data Bank Survey of Fukuoka prefecture in 1998. Dental health condition including number of teeth was examined by dentists. Data from 204 subjects (88 male, 116 female) who completed nonfasting venous blood examination including lipid peroxide and blood chemistry were analyzed. The examination included a medical questionnaire regarding smoking history, physical activity, alcohol consumption, educational duration, and regular dental care, anthropometric and manometric measurements. RESULTS: Albumin, lipids, and lipid peroxide in serum all were within the normal range. Number of teeth correlated positively with height and white blood cell count, and correlated negatively with lipid peroxide. In a multiple regression analysis to adjust for confounding factors, tooth number retained this correlation with lipid peroxide. By analysis of variance with a Bonferroni-Dunn correction, edentulous subjects showed significantly higher lipid peroxide than those retaining 20 teeth or more. CONCLUSION: The negative association between number of teeth and lipid peroxide links more teeth remaining with less oxidative stress in an 85-year-old population; this may decrease risk of atherosclerotic complications.

Relationship between chewing ability and 4-year mortality in a cohort of 80-year-old Japanese people.

OBJECTIVE: Poor oral health has been reported to be a risk indicator of mortality, however, few data are available regarding the relationship between chewing ability and mortality. We examined the relationship between self-assessed chewing ability and mortality in elderly subjects. DESIGN: Prospective study. SUBJECTS AND METHODS: Participating in the study were 697 people (277 males, 420 females) from 1282 individuals (80 years old) residing in Fukuoka Prefecture, Japan. Data on oral and systemic health status through questionnaires, accompanied by physical and laboratory blood examinations were obtained. Chewing ability was assessed based on the number of types of food each subject reported as able to chew by questionnaire. RESULTS: A total of 108 subjects died between 1998 and 2002. Those with the lowest number of chewable foods were associated with higher risk of mortality than those with the ability to chew all of the 15 types of food surveyed [hazard ratio (HR) = 2.38, 95% confidence interval (95% CI) = 1.07-5.29], though other parameters including current smoking, low serum albumin, and poor physical health status were more significant. Further, reduced chewing ability of soft foods increased the risk (HR = 2.65, 95% CI = 1.20-5.87). CONCLUSION: Chewing ability was associated with mortality in a population of 80-year-old community residents, and may be a predictor for survival rate.

Clinical significance and variation of the advanced calcified stylohyoid complex detected by panoramic radiographs among 80-year-old subjects.

OBJECTIVES: To evaluate the clinical significance and variation of a calcified stylohyoid complex associated with advanced calcification as detected on panoramic radiographs among 80-year-old subjects. METHODS: Panoramic radiographs of 659 patients (262 men and 397 women) and data of their general and dental health conditions were used for the evaluation of the relationship between a calcified stylohyoid complex and general health among 80-year-olds. This study was part of the 8020 Data Bank Survey, which was designed to collect the baseline data of general and dental health conditions in 80-year-old subjects. The morphology of the calcified stylohyoid complexes was allocated to one of 12 patterns. The lengths of the calcified stylohyoid complex were measured directly on the radiographs from the caudal margin of the tympanic plate to the tip of the styloid process. RESULTS: All of the stylohyoid complexes from the 659 panoramic radiographs could be allocated to one of 12 morphological patterns, and some of their radiographic findings suggested calcification of the carotid artery and lymph nodes. In 80-year-old subjects, the average length of the calcified stylohyoid complexes was 36.7 mm, and ranged from 0.0 mm to 153.0 mm. There appeared to be correlations between the length of the calcified stylohyoid complex and serum calcium concentration and heel bone density, but not with the Community Periodontal Index (CPI). CONCLUSIONS: Dentists should recognize the existence of morphological variation in calcified stylohyoid complexes, especially in length, apparent on panoramic radiographs of 80-year-old patients. In addition, the longer length of the calcified stylohyoid complexes in 80-year-old patients may be a predictor of bone density and high serum calcium concentration level. The findings from the present study may provide potentially life-saving information about elderly people.

Chewing ability and quality of life in an 80-year-old population.

As quality of life (QOL) could be influenced by oral status in the elderly, we examined whether chewing ability or number of teeth affected QOL in 80-year olds. A cross-sectional survey included dental examination, chewing self-assessment, and a QOL questionnaire. A total of 823 people who were 80 years old participated in this study. QOL was assessed in terms of satisfaction with physical condition, meals, daily living and social interactions, and with face-scale scores. After adjustment for gender, spouse and activities of daily living, dissatisfaction with social interactions was 3.9 times more prevalent in individuals able to chew four foods or fewer than in those chewing 15. Dissatisfaction with physical condition, meals and daily living, and poor face-scale scores, were 2.7, 2.4, 3.4, and 2.4 times more prevalent, respectively, in subjects chewing four foods or fewer. The number of teeth showed little effect. In conclusion, self-assessed chewing ability but not number of teeth was associated with QOL in 80-year-old subjects.

Quantitative detection of volatile sulfur compound- producing microorganisms in oral specimens using real-time PCR.

OBJECTIVE: It is well-known that some periodontopathic bacteria, especially Porphyromonas gingivalis, Fusobacterium nucleatum, Tannerella forsythia (formerly Bacteroides forsythus or Tan. forsythensis), and Treponema denticola, actively produce volatile sulfur compounds (VSCs), such as H2S and CH3SH. We previously reported a qualitative relationship between periodontopathic bacteria and VSCs; however, a quantitative analysis of periodontopathic bacteria in oral specimens is required for further characterization of the relationship between oral bacteria and VSCs. In this study, we report a real-time polymerase chain reaction (PCR) method for the quantitative analysis of VSC-producing bacteria in oral specimens. SUBJECTS AND METHODS: Specimens were collected from 22 patients who visited the Preventive Dentistry and Breath Odor Clinic of Kyushu Dental College. A real-time PCR assay using the TaqMan system, based on the 5'-3' exonuclease activity of Taq polymerase, was employed for the quantitative analysis of periodontopathic bacteria that produce VSCs. RESULTS: Using real-time PCR, we performed a quantitative analysis of P. gingivalis, F. nucleatum, Tan. forsythia, and T. denticola in the saliva, on the tongue coat, and in the subgingival plaque of patients with oral malodor. CONCLUSION: Real-time PCR using the TaqMan system can be used for the quantitative analysis of VSC-producing oral bacteria.

Activities of daily living and chewing ability in an 80-year-old population.

OBJECTIVES: The aim of this study was to determine whether chewing ability or number of intact teeth was related to performance of activities of daily living in 80-year olds. DESIGN: This was a cross-sectional survey including dental examinations, chewing self-assessment, and everyday function. SUBJECTS AND METHODS: A total of 823 people (309 males, 514 females) who were 80 years of age and resident in the Fukuoka Prefecture, Japan participated in this study. RESULTS: The mean number of intact teeth was 7.5 +/- 8.7; of the 15 food items offered, the mean number of foods chewed was 11.2 +/- 3.8. Function was independent in 713 subjects, and dependent in 93. After adjustment for gender, we found the number of foods chewed being linked to independent function by the multiple regression analysis (beta = 0.223, P < 0.0001); the number of intact teeth was only weakly related (beta = 0.077, P = 0.03). By logistic regression analysis, functional dependency was 7.5 times more prevalent in individuals capable of chewing four foods or fewer, and 3.3 times more prevalent in those chewing five to nine, than in those chewing all 15 items. No significant functional difference was related to the number of intact teeth. CONCLUSION: Chewing ability may be independently related with functional status in 80-year olds.

The assessment of methyl mercaptan, an important clinical marker for the diagnosis of oral malodor.

OBJECTIVE: This study aimed to determine the clinical assessment of volatile sulfur compound (VSCs) for the evaluation of noticeable oral malodor using gas chromatography (GC). METHODS: The oral malodor of 127 adult patients was investigated using the organoleptic test and GC, and the relation between the organoleptic evaluation and VSCs were analyzed. RESULTS: The optimum cut-off values of CH3SH, H2S and total VSC (CH3SH + H2S) to discriminate between the patients with and without noticeable oral malodor were obtained from ROC curves, and determined to be 0.44, 1.10 and 2.20 ng/10 ml, respectively. The logistic regression was analyzed for estimation of the association between an organoleptic evaluation greater than a slight level and the groups with CH3SH, H2S or total VSC with concentrations above the optimum cut-off value. Only CH3SH showed an independent association with noticeable oral malodor. CONCLUSIONS: It was evident that CH3SH was a more useful marker for the evaluation of oral malodor than H2S. Moreover, it appears CH3SH is the predominant causative factor of noticeable oral malodor.

Relationship of physical fitness to chewing in an 80-year-old population.

OBJECTIVE: Although tooth loss causes a decrease in masticatory ability, which may influence nutritional status, and impair an individual's general health including physical activity, little is known whether a decrease in chewing ability could result in deterioration in physical fitness in a very elderly population. Thus, the present study evaluated the relationship of chewing ability or teeth number with measures of physical fitness in a sample of 80-years-old in Japan. DESIGN: Cross-sectional survey. SUBJECTS AND METHODS: A total of 1282 people who were 80-years old and resided in the Fukuoka Prefecture were approached. A total of 697 individuals (277 male, 420 female) agreed to participate. RESULTS: Chewing food number and teeth number were related positively with physical fitness measurements of hand grip strength, leg extensor strength, leg extensor power, stepping rate, and one-leg standing time. However, the significant relationship between the number of teeth and physical ability disappeared after adjustment for various confounders, using multiple regression analysis or logistic regression analysis. On the other hand, the relationship of chewing ability with physical fitness measurements of leg extensor strength, one-leg standing time, or isokinetic leg extensor power remained significant even after adjustment for these confounders. CONCLUSION: There is a relationship between perceived chewing ability (number of foods considered chewable) and physical fitness in this 80-year-old population. Chewing ability may be an independent predictor of physical fitness, thus preventative dental care aimed at preserving chewing ability may be able to enhance activities of daily life and quality of life in very elderly individuals.

The relationship between the presence of periodontopathogenic bacteria in saliva and halitosis.

OBJECTIVE: To evaluate the association between the presence of periodontal pathogenic bacteria in saliva and halitosis in mouth air. DESIGN: Cross-sectional microbiological and clinical oral examination of adult patients. SUBJECTS: 101 adult patients (25 males, 76 females) who attended the Preventive Dentistry and Breath Odour Clinic of Kyushu Dental College. Their average age was 50.0+/-13.5 years old (mean +/- SD). SETTING: The subjects were classified into three groups: halitosis subjects with a probing depth (PD) > or = 4mm (P group), halitosis subjects without PD > or = 4mm (H group), and non-halitosis subjects without PD > or = 4mm (C group). METHODS: All subjects received a periodontal examination. Volatile sulphur compounds (VSC: hydrogen sulphide and methyl mercaptan) were measured using gas chromatography. The presence of Bacteroides forsythus, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia in the saliva was detected by polymerase chain reaction. RESULTS AND CONCLUSION: The presence of B. forsythus, P. gingivalis and P. intermedia influenced the production of VSC. Specifically, the presence of B. forsythus in subjects with periodontitis was strongly correlated to the concentration of VSC in mouth air.

Association of body mass index with blood pressure in 80-year-old subjects.

OBJECTIVE: Little data are available on the association between obesity and high blood pressure in elderly individuals, particularly in subjects over 80 years of age. The aim of the present study was to determine the association between body mass index (BMI) and blood pressure in 80-year-old subjects. METHODS: This study was part of the 8020 Data Bank Survey, which was designed to collect the baseline data of systemic and dental health conditions in 80-year-old subjects. We studied the cross-sectional association of BMI with blood pressures in 645 Japanese (258 men and 387 women), who were 80 years old. RESULTS: Mean systolic blood pressure rose from 146.6 mmHg in the first quintile of BMI to 147.5 mmHg in the second, 150.3 mmHg in the third, 151.6 mmHg in the fourth, and 156.4 mmHg in the fifth quintiles (test for trend, P = 0.006). Mean diastolic blood pressure rose from 75.8 mmHg in the lowest quintile of BMI to 81.8 mmHg in the highest (test for trend, P = 0.002). We performed multiple regression analysis, controlling for factors known to influence blood pressure values, such as sex, alcohol intake, current smoking status and serum glucose, total cholesterol and creatinine concentrations. The association between BMI and systolic and diastolic blood pressure, respectively, was highly statistically significant in all analyses. CONCLUSION: These results show that a close relationship is present between obesity and high blood pressure, even in very old subjects.

Relationship between tooth loss and electrocardiographic abnormalities in octogenarians.

Recent reports have suggested that periodontal disease is a risk factor for coronary heart disease (CHD). However, little is known about the relationship between periodontal disease and CHD in the very elderly. Therefore, we evaluated the association between tooth loss and abnormal ECG findings in octogenarians. Of the 1,282 octogenarians in Fukuoka Prefecture, Japan, 697 participated. Oral examinations--including a tooth count and an assessment of the Community Periodontal Index--and a 12-lead ECG were performed. Logistic regression analysis revealed that individuals with < 20 teeth had increased prevalence of ST segment depression, and T-wave abnormalities, after we adjusted for gender, smoking, serum cholesterol and glucose, blood pressure, and body mass index. Compared with individuals with > or = 20 teeth, edentulous individuals had an increased prevalence of T-wave abnormalities and arrhythmias after adjustment for coronary risk factors. We conclude that tooth loss may be an independent predictor of abnormal ECG findings in octogenarians.

Isolation, cloning, and expression of an acid phosphatase containing phosphotyrosyl phosphatase activity from Prevotella intermedia.

A novel acid phosphatase containing phosphotyrosyl phosphatase (PTPase) activity, designated PiACP, from Prevotella intermedia ATCC 25611, an anaerobe implicated in progressive periodontal disease, has been purified and characterized. PiACP, a monomer with an apparent molecular mass of 30 kDa, did not require divalent metal cations for activity and was sensitive to orthovanadate but highly resistant to okadaic acid. The enzyme exhibited substantial activity against tyrosine phosphate-containing peptides derived from the epidermal growth factor receptor. On the basis of N-terminal and internal amino acid sequences of purified PiACP, the gene coding for PiACP was isolated and sequenced. The PiACP gene consisted of 792 bp and coded for a basic protein with an M(r) of 29,164. The deduced amino acid sequence exhibited striking similarity (25 to 64%) to those of members of class A bacterial acid phosphatases, including PhoC of Morganella morganii, and involved a conserved phosphatase sequence motif that is shared among several lipid phosphatases and the mammalian glucose-6-phosphatases. The highly conservative motif HCXAGXXR in the active domain of PTPase was not found in PiACP. Mutagenesis of recombinant PiACP showed that His-170 and His-209 were essential for activity. Thus, the class A bacterial acid phosphatases including PiACP may function as atypical PTPases, the biological functions of which remain to be determined.

Sequencing, expression and biochemical characterization of the Porphyromonas gingivalis pepO gene encoding a protein homologous to human endothelin-converting enzyme.

We have determined the nucleotide sequence of the clone pAL2 obtained from Porphyromonas gingivalis 381 in the previous study [Ansai et al. (1995) Microbiology 141, 2047-20521. The DNA sequence analysis of this fragment revealed one complete ORF and one incomplete ORF. The ORF encoded a protein (PgPepO) of 690 amino acids with a calculated molecular weight of 78796. The deduced amino acid sequence exhibited a significant homology with human endothelin-converting enzyme (ECE)-1. Recombinant PgPepO was purified to homogeneity and characterized. The purified enzyme was strongly inhibited by phosphoramidon, and converted big endothelin-1 to endothelin-1. Furthermore, the purified PgPepO strongly cross-reacted with a monoclonal antibody against rat ECE-1. These results indicate that PgPepO has striking similarity to mammalian ECE in structure and function.

Purification and characterization of alkaline phosphatase containing phosphotyrosyl phosphatase activity from the bacterium Prevotella intermedia.

A novel alkaline phosphatase, designated PiALP, has been purified and characterized from Prevotella intermedia ATCC 25611, an anaerobe implicated in progressive periodontal disease. The enzyme was a homodimer of apparently identical subunits of Mr 54 kDa. Thiol-reducing agents completely inhibited the purified enzyme. The enzyme was highly stable even at 80 degrees C. It exhibited substantial activity against tyrosine-phosphate-containing Raytide. The phosphatase activity was sensitive to orthovanadate and Zn2+ but highly resistant to okadaic acid. The amino acid sequence of peptides derived from PiALP showed a high degree of identity (65%) with alkaline phosphatases from Zymomonas mobilis and Synechococcus. The present results imply that PiALP might represent a new family of alkaline phosphotyrosyl phosphatases which has not been described previously.

A murC gene in Porphyromonas gingivalis 381.

The gene encoding a 51 kDa polypeptide of Porphyromonas gingivalis 381 was isolated by immunoblotting using an antiserum raised against P. gingivalis alkaline phosphatase. DNA sequence analysis of a 2.5 kb DNA fragment containing a gene encoding the 51 kDa protein revealed one complete and two incomplete ORFs. Database searches using the FASTA program revealed significant homology between the P. gingivalis 51 kDa protein and the MurC protein of Escherichia coli, which functions in peptidoglycan synthesis. The cloned 51 kDa protein encoded a functional product that complemented an E. coli murC mutant. Moreover, the ORF just upstream of murC coded for a protein that was 31% homologous with the E. coli MurG protein. The ORF just downstream of murC coded for a protein that was 17% homologous with the Streptococcus pneumoniae penicillin-binding protein 2B (PBP2B), which functions in peptidoglycan synthesis and is responsible for antibiotic resistance. These results suggest that P. gingivalis contains a homologue of the E. coli peptidoglycan synthesis gene murC and indicate the possibility of a cluster of genes responsible for cell division and cell growth, as in the E. coli mra region.