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1.
Am J Transplant ; 13(10): 2722-9, 2013 Oct.
Article in English | MEDLINE | ID: mdl-24007361

ABSTRACT

Primary graft failure and chronic lung allograft dysfunction (CLAD) limit lung transplant long-term outcomes. Various lung diseases have been correlated with surfactant protein (SP) expression and polymorphisms. We sought to investigate the role of SP expression in lung allografts prior to implantation, in relation to posttransplant outcomes. The expression of SP-(A, B, C, D) mRNA was assayed in 42 allografts. Posttransplant assessments include pulmonary function tests, bronchoscopy, broncho-alveolar lavage fluid (BALF) and biopsies to determine allograft rejection. BALF was assayed for SP-A, SP-D in addition to cytokines IL-8, IL-12 and IL-2. The diagnosis of CLAD was evaluated 6 months after transplantation. Lung allografts with low SP-A mRNA expression prior to implantation reduced survival (Log-rank p < 0.0001). No association was noted for the other SPs. Allografts with low SP-A mRNA had greater IL-2 (p = 0.03) and IL-12 (p < 0.0001) in the BALF and a greater incidence of rejection episodes (p = 0.003). Levels of SP-A mRNA expression were associated with the SP-A2 polymorphisms (p = 0.015). Specifically, genotype 1A1A(0) was associated with lower SP-A mRNA expression (p < 0.05). Lung allografts with low levels of SP-A mRNA expression are associated with reduced survival. Lung allograft SP-A mRNA expression appears to be associated with SP-A gene polymorphisms.


Subject(s)
Graft Rejection/genetics , Lung Diseases/surgery , Lung Transplantation , Polymorphism, Genetic/genetics , Pulmonary Surfactant-Associated Protein A/genetics , Adult , Aged , Allografts , Bronchoalveolar Lavage Fluid , Cytokines/genetics , Female , Follow-Up Studies , Graft Rejection/diagnosis , Graft Rejection/mortality , Humans , Male , Middle Aged , Pilot Projects , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Prognosis , Prospective Studies , Pulmonary Surfactant-Associated Protein D/genetics , RNA, Messenger/genetics , Retrospective Studies , Survival Rate
2.
Transpl Infect Dis ; 12(6): 551-4, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20553438

ABSTRACT

Cystic fibrosis (CF) lung transplant recipients infected with Burkholderia cenocepacia have a worse survival rate after lung transplantation than those who are not infected with this organism. The decreased survival is predominantly due to recurrent B. cenocepacia infection, with the majority of affected recipients succumbing within 3 months after transplant. B. cepacia complex (BCC) sepsis is one of the defining criteria for cepacia syndrome, an almost universally fatal necrotizing pneumonic illness. We report 2 CF patients who were long-term survivors of B. cenocepacia sepsis after lung transplantation. The aim of this report is to demonstrate that, although survival of B. cenocepacia sepsis after lung transplantation is extremely uncommon, with aggressive multidisciplinary management, long-term survival remains a realistic objective.


Subject(s)
Burkholderia Infections/mortality , Burkholderia cepacia complex/isolation & purification , Cystic Fibrosis/complications , Cystic Fibrosis/mortality , Lung Transplantation/adverse effects , Sepsis/mortality , Adult , Anti-Bacterial Agents/therapeutic use , Burkholderia Infections/microbiology , Burkholderia Infections/surgery , Burkholderia cepacia complex/classification , Burkholderia cepacia complex/drug effects , Cystic Fibrosis/drug therapy , Cystic Fibrosis/surgery , Empyema, Pleural/microbiology , Empyema, Pleural/surgery , Female , Humans , Lung/surgery , Lung Abscess/microbiology , Lung Abscess/surgery , Lung Transplantation/mortality , Male , Sepsis/drug therapy , Sepsis/microbiology , Sepsis/surgery , Survival Rate , Survivors , Young Adult
3.
Rev Sci Instrum ; 80(7): 074501, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19655969

ABSTRACT

We discuss the design, operation, and performance of a vacuum setup constructed for use in zero (or reduced) gravity conditions to initiate collisions of fragile millimeter-sized particles at low velocity and temperature. Such particles are typically found in many astronomical settings and in regions of planet formation. The instrument has participated in four parabolic flight campaigns to date, operating for a total of 2.4 h in reduced-gravity conditions and successfully recording over 300 separate collisions of loosely packed dust aggregates and ice samples. The imparted particle velocities achieved range from 0.03 to 0.28 m s(-1) and a high-speed, high-resolution camera captures the events at 107 frames/s from two viewing angles separated by either 48.8 degrees or 60.0 degrees. The particles can be stored inside the experiment vacuum chamber at temperatures of 80-300 K for several uninterrupted hours using a built-in thermal accumulation system. The copper structure allows cooling down to cryogenic temperatures before commencement of the experiments. Throughout the parabolic flight campaigns, add-ons and modifications have been made, illustrating the instrument flexibility in the study of small particle collisions.


Subject(s)
Cold Temperature , Particle Accelerators/instrumentation , Weightlessness , Computer-Aided Design , Copper , Dust , Equipment Design , Ice , Motion , Vacuum
4.
Am J Transplant ; 7(5): 1271-7, 2007 May.
Article in English | MEDLINE | ID: mdl-17456202

ABSTRACT

Selection criteria for organ transplantation have evolved over time. Age has been revisited periodically. We studied the outcome of lung transplant adjusted by age in a single center transplant population. We matched the 42 lung graft recipients older than 60 years transplanted by July 1999 to younger controls by lung disease, transplant era within 2 years, type of transplant and gender. The female to male ratios were 17/25 among the older cohort (median age 61.6 years), and 15/27 (median age 51.9 years) among the matched younger. Survival analysis demonstrated a significant difference: at 1 year, 60% versus 86%, and at 5 years, 37% versus 57%, for older and younger, respectively, p=0.005. Excess annual mortality, calculated with the declining exponential approximation to life expectancy (DEALE), showed an older/younger ratio of 1.9. Eleven deaths occurred within 6 months among the older patients, 10 due to infection. After 6 months, there were 20 more deaths, 6 due to malignancy, 5 to Bronchiolitis Obliterans Syndrome (BOS), 3 to infection and 6 to other causes. Among the younger there were 6 deaths within 6 months and 12 more thereafter; among the latter, 8 were due to BOS. Despite stringent selection, lung transplant recipients older than 60 years show increased mortality even after adjusting for their expected higher age-related mortality.


Subject(s)
Lung Transplantation/mortality , Patient Selection , Transplantation/physiology , Adult , Age Factors , Bronchiolitis Obliterans/etiology , Bronchiolitis Obliterans/mortality , Case-Control Studies , Cohort Studies , Data Interpretation, Statistical , Female , Graft Rejection/physiopathology , Humans , Infections/etiology , Infections/mortality , Length of Stay/statistics & numerical data , Lung Transplantation/adverse effects , Lung Transplantation/statistics & numerical data , Male , Middle Aged , Retrospective Studies , Risk Factors , Survival Rate , Treatment Outcome
5.
Am J Transplant ; 6(8): 1930-8, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16889547

ABSTRACT

Gastro-esophageal reflux and related pulmonary bile acid aspiration were prospectively investigated as possible contributors to postlung transplant bronchiolitis obliterans syndrome (BOS). We also studied the impact of aspiration on pulmonary surfactant collectin proteins SP-A and SP-D and on surfactant phospholipids--all important components of innate immunity in the lung. Proximal and distal esophageal 24-h pH testing and broncho-alveolar lavage fluid (BALF) bile acid assays were performed prospectively at 3-month posttransplant in 50 patients. BALF was also assayed for SP-A, SP-D and phospholipids expressed as ratio to total lipids: phosphatidylcholine; dipalmitoylphosphatidylcholine; phosphatidylglycerol (PG); phosphatidylinositol; sphingomyelin (SM) and lysophosphatidylcholine. Actuarial freedom from BOS was assessed. Freedom from BOS was reduced in patients with abnormal (proximal and/or distal) esophageal pH findings or BALF bile acids (Log-rank Mantel-Cox p < 0.05). Abnormal pH findings were observed in 72% (8 of 11) of patients with bile acids detected within the BALF. BALF with high levels of bile acids also had significantly lower SP-A, SP-D, dipalmitoylphosphatidylcholine; PG and higher SM levels (Mann-Whitney, p < 0.05). Duodeno-gastro-esophageal reflux and consequent aspiration is a risk factor for the development of BOS postlung transplant. Bile acid aspiration is associated with impaired lung allograft innate immunity manifest by reduced surfactant collectins and altered phospholipids.


Subject(s)
Bile Acids and Salts/metabolism , Immunity, Innate/immunology , Lung Transplantation/immunology , Pulmonary Surfactant-Associated Protein A/immunology , Pulmonary Surfactant-Associated Protein D/immunology , Respiratory Aspiration/physiopathology , Bronchoalveolar Lavage Fluid/immunology , Follow-Up Studies , Humans , Hydrogen-Ion Concentration , Phosphatidylglycerols/metabolism , Sphingomyelins/metabolism , Transplantation, Homologous/immunology
6.
Am J Transplant ; 6(1): 183-9, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16433773

ABSTRACT

Previous studies suggest that bilateral (BLT) compared with single lung transplantation (SLT) for patients with chronic obstructive pulmonary disease (COPD) results in improved long-term survival. The effect of transplant operation on bronchiolitis obliterans syndrome (BOS) is unknown. A retrospective study of all lung transplant recipients with pre-transplant diagnoses of COPD at the University of Toronto and at Duke University was performed. Data collected were age, gender, date and type of transplant, acute rejection, survival, presence and time of BOS. 221 (bilateral n = 101, single n = 120) patients met our criteria. Patients with BLT were younger (53.0 vs. 55.3 years; p = 0.034), more likely to be male (56.3% vs. 42.4%; p = 0.039) and more likely to be transplanted at the University of Toronto (79.6% vs. 16.1%; p < 0.001). Freedom from BOS was similar at 1 year post-transplant. However, BLT recipients were more commonly free from BOS 3 years (57.4% vs. 50.7%) and 5 years (44.5% vs. 17.9%) post-transplant (p = 0.024). Survival of BLT was better than SLT recipients at 3 and 5 years post-transplant (BLT vs. SLT: 67.5% vs. 61.1% and 60.7% vs. 34.1%, respectively; p = 0.018). Similar trends on survival were observed after development of BOS. BLT results in lower rates of BOS in patients with COPD that are eligible for both SLT and BLT.


Subject(s)
Bronchiolitis Obliterans/surgery , Lung Transplantation/mortality , Pulmonary Disease, Chronic Obstructive/surgery , Bronchiolitis Obliterans/mortality , Female , Humans , Male , Middle Aged , Pulmonary Disease, Chronic Obstructive/mortality , Syndrome , Treatment Outcome
7.
Transplantation ; 72(11): 1783-6, 2001 Dec 15.
Article in English | MEDLINE | ID: mdl-11740388

ABSTRACT

BACKGROUND: Posttransplant lymphoproliferative disease (PTLD) is now a widely recognized complication of lung transplantation. In the current study, we present our experience with PTLD over a 15-year period, which includes the incidence rates in 242 lung allografts and the relative risk of developing PTLD in 146 patients with known pretransplantation Epstein-Barr virus (EBV) status. METHODS: Inpatient and outpatient charts of 300 consecutive lung transplant recipients between 1984 and 1999 were retrospectively reviewed. RESULTS: Twelve cases of PTLD were observed for a total incidence rate of 5.0%. Ten of these patients had pretransplantation EBV testing, and the consequent increase in relative risk for patients who were EBV negative was 6.8-fold. The mean time between organ transplantation and tissue diagnosis of PTLD was 17.6 months. Total 1-year survival rate from the time of diagnosis for the cohort was 58%, whereas 2-year survival rate was 50%. Median survival for the six patients who died was 4.5 months. CONCLUSIONS: These data suggest that although EBV seronegativity does carry a 6.8-fold increase in the relative risk of developing PTLD, long-term survival despite the development of PTLD can be achieved, and thus EBV seronegativity by itself should not be considered a contraindication to lung transplantation.


Subject(s)
Antigen-Antibody Reactions , Herpesvirus 4, Human/immunology , Lung Transplantation/adverse effects , Lymphoproliferative Disorders/etiology , Adolescent , Adult , Cohort Studies , Female , Humans , Incidence , Lymphoproliferative Disorders/epidemiology , Male , Middle Aged , Retrospective Studies , Risk Factors , Survival Analysis , Time Factors
8.
Proc Natl Acad Sci U S A ; 98(15): 8519-24, 2001 Jul 17.
Article in English | MEDLINE | ID: mdl-11438702

ABSTRACT

Subunit rotation within the F(1) catalytic sector of the ATP synthase has been well documented, identifying the synthase as the smallest known rotary motor. In the membrane-embedded F(O) sector, it is thought that proton transport occurs at a rotor/stator interface between the oligomeric ring of c subunits (rotor) and the single-copy a subunit (stator). Here we report evidence for an energy-dependent rotation at this interface. F(O)F(1) was expressed with a pair of substituted cysteines positioned to allow an intersubunit disulfide crosslink between subunit a and a c subunit [aN214C/cM65C; Jiang, W. & Fillingame, R. H. (1998) Proc. Natl. Acad. Sci. USA 95, 6607--6612]. Membranes were treated with N,N'-dicyclohexyl-[(14)C]carbodiimide to radiolabel the D61 residue on less than 20% of the c subunits. After oxidation to form an a--c crosslink, the c subunit properly aligned to crosslink to subunit a was found to contain very little (14)C label relative to other members of the c ring. However, exposure to MgATP before oxidation significantly increased the radiolabel in the a-c crosslink, indicating that a different c subunit was now aligned with subunit a. This increase was not induced by exposure to MgADP/P(i). Furthermore, preincubation with MgADP and azide to inhibit F(1) or with high concentrations of N,N'-dicyclohexylcarbodiimide to label most c subunits prevented the ATP effect. These results provide evidence for an energy-dependent rotation of the c ring relative to subunit a.


Subject(s)
Proton-Translocating ATPases/chemistry , Adenosine Triphosphate/metabolism , Cross-Linking Reagents , Dicyclohexylcarbodiimide/metabolism , Energy Transfer , Enzyme Inhibitors/metabolism , Escherichia coli/enzymology , Protein Conformation , Proton-Translocating ATPases/antagonists & inhibitors , Proton-Translocating ATPases/metabolism
12.
J Heart Lung Transplant ; 20(3): 288-96, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11257554

ABSTRACT

BACKGROUND: It is well documented that malnourished and/or obese surgical patients have increased morbidity and mortality post-operatively. Only a few studies investigating the effect of nutritional status on mortality are available pertaining to the transplant population. Since limited data are available on the nutritional status and its effects on mortality in the lung transplant population, we sought to ascertain whether there is an association between mortality and preoperative nutritional status. METHODS: We examined mortality during the first 3 months after transplantation. Patients were grouped by body mass index (BMI) categories as < 17 kg/m(2), 17 to < 20 kg/m(2), 20 to 25 kg/m(2) (reference group), > 25 to 27 kg/m(2), and > 27 kg/m(2). Additional risk factors retrieved from the pre-transplant records included age, gender, diagnosis, energy requirements, protein requirements, protein and caloric intake, and weight history. Logistic regression for univariate and multivariate analysis for mortality used recipient age, gender, disease category, pre-transplant cytomegalovirus (CMV) serology, transplant type (single or bilateral), and donor age, gender, and CMV serology. RESULTS: The likelihood estimates or odds ratios (ORs) of the risk of death within 90 days of lung transplantation for the BMI categories compared to the reference group were 3.7 for BMI < 17 kg/m(2) (p = 0.085), 1.6 for BMI < 17 to 20 kg/m(2) (p = 0.455), 3.5 for BMI > 25 to 27 kg/m(2) (p = 0.069), and 5.0 for BMI > 27 kg/m(2) (p = 0.003). CONCLUSIONS: In patients with a pre-transplant BMI < 17 kg/m(2) or > 25 kg/m(2) the risk of dying within 90 days post-transplant was increased. In patients with a pre-transplant BMI of > 27 kg/m(2) the risk was significantly higher in than the reference group.


Subject(s)
Body Mass Index , Lung Transplantation/mortality , Nutritional Status , Adult , Cause of Death , Female , Humans , Logistic Models , Male , Middle Aged , Predictive Value of Tests , Retrospective Studies , Risk Factors
14.
Am J Respir Crit Care Med ; 163(1): 43-8, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11208624

ABSTRACT

As a result of concern over excessive mortality after lung transplantation, many transplant programs refuse to accept cystic fibrosis (CF) patients infected with Burkholderia cepacia. As a significant proportion of patients with CF in our community are infected with this organism, we have continued to provide lung transplantation as an option. A retrospective review was conducted of medical records of all patients with CF transplanted between March 1988 and September 1996. Fifty-six transplant procedures were performed in 53 recipients with CF between March 1988 and September 1996. Twenty-eight had B. cepacia isolated pretransplant and 25 remaining positive post-transplant. Of the 53 recipients, 19 have died (15 of 28 [54%] B. cepacia positive and 4 of 25 [16%] B. cepacia negative). B. cepacia was responsible for or involved in 14 deaths. Nine of the deaths occurred in the first 3 mo post-transplantation. One-year survival was 67% for B. cepacia positive patients and 92% for B. cepacia negative patients. Recent modifications in antimicrobial and immunosuppressive therapy since 1995 have resulted in no deaths early post-transplant in the last five patients transplanted. We conclude that early mortality in patients with CF infected with B. cepacia is significantly higher than in those not infected with B. cepacia. Modifications in post-transplant medical therapy may improve outcome.


Subject(s)
Burkholderia Infections/etiology , Burkholderia cepacia , Cystic Fibrosis/complications , Lung Transplantation/adverse effects , Adult , Burkholderia Infections/complications , Burkholderia Infections/mortality , Burkholderia cepacia/isolation & purification , Female , Humans , Immunosuppression Therapy , Male , Middle Aged , Prognosis , Retrospective Studies
15.
Chest ; 117(2): 476-81, 2000 Feb.
Article in English | MEDLINE | ID: mdl-10669693

ABSTRACT

STUDY OBJECTIVE: Osteoporosis is a well-recognized complication of lung transplantation that may significantly impair the quality of life of transplant recipients. We performed a prospective study of bone mineral density (BMD) before and after transplantation to determine the degree of bone mass loss associated with lung transplantation Patients and design: We conducted a prospective study of BMD in 28 patients with various end-stage respiratory diseases pretransplantation and 6 to 12 months posttransplantation. The BMD of the lumbar spine (LS) and femoral neck (FN) were measured. All 28 patients were treated only with vitamin D and calcium supplementation posttransplant. The primary endpoint was the percentage change in BMD. The secondary endpoint was the incidence of fractures posttransplant. A univariate analysis was conducted to determine the various risk factors associated with bone mass loss pretransplant and posttransplant. RESULTS: Prior to transplantation, moderate to severe bone disease was evident. The mean (+/- SD) pretransplant T score (the number of SDs from the peak bone mass) and Z score (the number of SDs from the age-matched mean) for the LS were -1.72 +/- 1.37 and -1.44 +/- 1.31, respectively. The mean pretransplant T score and Z score for the FN were -2.65 +/- 1.01 and -1.5 +/- 1.43, respectively. Within 6 to 12 months posttransplant, the mean BMD for the LS decreased by 4.76% (p < 0.001), while the mean BMD for the FN decreased by 5.3% (p < 0.001). Five of the 28 patients (18%) suffered osteoporotic fractures posttransplant, while no fractures were documented pretransplant. The cumulative steroid dose posttransplant was associated with a drop in BMD for the LS and FN (r = 0.39, p = 0.039 and r = 0.63, p < 0.001, respectively), while a negative association was found between cumulative steroid use pretransplant and baseline LS and FN T scores (r = -0.4, p = 0. 02 and r = -0.43, p = 0.023, respectively). CONCLUSION: Within 6 to 12 months after lung transplantation, there is a significant decrease in BMD at both the LS and FN levels (approximately 5%) despite vitamin D and calcium supplementation. This drop in BMD is associated with a relatively high incidence of osteoporotic fractures posttransplant.


Subject(s)
Bone Density/physiology , Lung Transplantation/physiology , Osteoporosis/physiopathology , Postoperative Complications/physiopathology , Absorptiometry, Photon , Adult , Aged , Bone and Bones/physiopathology , Female , Follow-Up Studies , Fractures, Spontaneous/diagnosis , Fractures, Spontaneous/physiopathology , Humans , Male , Middle Aged , Osteoporosis/diagnosis , Postoperative Complications/diagnosis , Prospective Studies , Risk Factors
16.
Am J Respir Crit Care Med ; 157(6 Pt 1): 1822-8, 1998 Jun.
Article in English | MEDLINE | ID: mdl-9620912

ABSTRACT

Acute allograft rejection in animals and humans has been associated with increased nitric oxide production in the graft. Exhaled nitric oxide (ENO) measurement is a noninvasive method of assessing inflammation in airway diseases, e.g., asthma, which might be applicable to lung transplant recipients. Over 12 months, ENO of lower respiratory origin was measured in 108 lung transplant recipients with a mean time after transplant of 1,083 d. ENO (mean +/- SEM; ppb) in stable patients (19.5 +/- 1.1; p < 0.001) was not different from that of healthy controls (23.8 +/- 3.2). ENO was significantly higher in episodes of clinical acute rejection (51.1 +/- 6.3) compared with stable patients but not elevated in bronchiolitis obliterans syndrome (18.6 +/- 1.5) or pulmonary infection (25.9 +/- 4.0). A retrospective analysis of bronchoscopy findings and concurrent ENO (n = 99) showed that ENO did not vary according to histological findings (normal, acute rejection grade I, nonspecific inflammatory change) or with a positive BAL culture. ENO was not correlated with differential lymphocyte and neutrophil counts. ENO appears to be a valid marker of clinical acute rejection in human lung transplantation as distinct from infection or bronchiolitis obliterans. Furthermore, bronchoscopic findings in the absence of a clinical illness were not associated with a rise in ENO.


Subject(s)
Breath Tests , Graft Rejection/diagnosis , Lung Transplantation , Nitric Oxide/analysis , Adult , Biomarkers/analysis , Bronchiolitis Obliterans/metabolism , Bronchoscopy , Female , Graft Rejection/metabolism , Humans , Male , Middle Aged , Nitric Oxide/metabolism , Respiratory Tract Infections/metabolism
17.
Radiology ; 206(2): 519-24, 1998 Feb.
Article in English | MEDLINE | ID: mdl-9457207

ABSTRACT

PURPOSE: To define the imaging features of lymphoproliferative disorders that occur after lung transplantation. MATERIALS AND METHODS: In a retrospective review of the cases of 246 patients who had undergone lung transplantation (62 single- and 184 double-lung transplants) between 1987 and 1997, the authors found nine patients (seven men and two women, aged 16-59 years [mean, 42.2 years]) with posttransplantation lymphoproliferative disorders. All imaging, clinical, and pathologic findings pertaining to these disorders were reviewed. RESULTS: Eight of the nine patients had isolated intrathoracic disease. The most common abnormality (six patients) was the presence of multiple, well-defined pulmonary nodules. These nodules, when multiple, had basilar and peripheral predominance. Other abnormal features included hilar or mediastinal adenopathy (two patients), a consolidated upper lobe (one patient), a pleural mass (one patient), and bulky abdominal lymphadenopathy (one patient with pathologically proved Hodgkin lymphoma). Three patients had nodules with a surrounding area of ground-glass opacity (halo sign), and one patient had multiple ill-defined areas of centrilobular opacity. Air bronchograms were not often seen, and pleural effusions were absent. CONCLUSION: The presence of well-defined pulmonary nodules in a patient who has undergone lung transplantation should raise concern about the possibility of posttransplantation lymphoproliferative disorder. In such cases, performance of pathologic studies should be expedited.


Subject(s)
Lung Diseases/diagnostic imaging , Lung Diseases/etiology , Lung Transplantation , Lymphoproliferative Disorders/diagnostic imaging , Lymphoproliferative Disorders/etiology , Postoperative Complications/diagnostic imaging , Adult , Female , Humans , Incidence , Lung Diseases/epidemiology , Lymphoproliferative Disorders/epidemiology , Male , Postoperative Complications/epidemiology , Retrospective Studies , Solitary Pulmonary Nodule/diagnostic imaging , Tomography, X-Ray Computed
18.
CMAJ ; 157(12): 1734-5, 1997 Dec 15.
Article in English | MEDLINE | ID: mdl-9441039
20.
Biochim Biophys Acta ; 1275(1-2): 96-100, 1996 Jul 18.
Article in English | MEDLINE | ID: mdl-8688454

ABSTRACT

We recently demonstrated that the gamma subunit in soluble F1-ATPase from Escherichia coli rotates relative to surrounding beta subunits during catalytic turnover (Duncan et al. (1995) Proc. Natl. Acad. Sci. USA 92, 10964-10968). Here, we extend our studies to the more physiologically relevant membrane-bound F0F1 complex. It is shown that beta D380C-F1, containing a beta-gamma intersubunit disulfide bond, can bind to F1-depleted membranes and can restore coupled membrane activities upon reduction of the disulfide. Using a dissociation/reconstitution approach with crosslinked beta D380C-F1, beta subunits containing an N-terminal Flag epitope (beta flag) were incorporated into the two non-crosslinked beta positions and the hybrid F1 was reconstituted with membrane-bound F0. Following reduction and ATP hydrolysis, reoxidation resulted in a significant amount of crosslinking of beta flag to the gamma subunit. This demonstrates that gamma rotates within F1 during catalytic turnover by membrane-bound F0-F1. Furthermore, the rotation of gamma is functionally coupled to F0, since preincubation with DCCD to modify F0 blocked rotation.


Subject(s)
Adenosine Triphosphate/metabolism , Proton-Translocating ATPases/chemistry , Amino Acid Sequence , Base Sequence , Cell Membrane/enzymology , Hydrolysis , Molecular Sequence Data , Proton-Translocating ATPases/metabolism , Rotation
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