Quantitative proteomics analysis of ClpS-mediated rifampicin resistance in Mycobacterium / 生物工程学报

Adaptor protein ClpS is an essential regulator of prokaryotic ATP-dependent protease ClpAP, which delivers certain protein substrates with specific amino acid sequences to ClpAP for degradation. However, ClpS also functions as the inhibitor of the ClpAP-mediated protein degradation for other proteins. Here, we constructed the clpS-overexpression Mycobacterium smegmatis strain, and showed for the first time that overexpression of ClpS increased the resistance of M. smegmatis to rifampicin that is one of most widely used antibiotic drugs in treatment of tuberculosis. Using quantitative proteomic technology, we systematically analyzed effects of ClpS overexpression on changes in M. smegmatis proteome, and proposed that the increased rifampicin resistance was caused by ClpS-regulated drug sedimentation and drug metabolism. Our results indicate that the changes in degradation related proteins enhanced drug resistance and quantitative proteomic analysis is an important tool for understanding molecular mechanisms responsible for bacteria drug resistance.

Selección de cepas nativas con actividad quitino-proteolítica de bacillus sp aisladas de suelos tropicales / Selecting native Bacillus sp strains having chitinolytic and proteolytic activity which have been isolated from tropical soils

El objetivo de este trabajo fue la selección de cepas nativas del género Bacillus con actividad quitinolíticay proteolítica, en suelo tropical en la costa de Oaxaca, México. Se aislaron 150 cepas, de las cuales 22fueron seleccionadas por presentar actividad quitinolítica y proteolítica. Dicha actividad se evaluó porla formación de halo de hidrólisis alrededor de la colonia en medios de cultivo suplementados con quitinacoloidal al 5% y leche descremada al 1% respectivamente. Las cepas LUM B001, B003, B013, B015y B065 presentaron mayor actividad quitinolítica y proteolítica, por lo que tienen el potencial para serevaluadas en control biológico de hongos fitopatógenos. Se encontró al género Bacillus distribuido ensuelos cultivados y no cultivados, no se encontraron diferencias estadísticas según el cultivo establecido(P<0,05), sin embargo se encontraron diferencias significativas (P<0,05) entre las zonas estudiadas, correspondiendolas menores recuperaciones de cepas a los terrenos del municipio de Tututepec, Oaxaca.

This work was aimed at selecting native strains from the Bacillus genus having chitinolytic and proteolytic activityfrom soil from the tropical coast of Oaxaca, Mexico. 150 strains were isolated, 22 of which were selectedas they presented chitinolytic and proteolytic activity. Such activity was assessed by the formation of a hydrolysishalo around the colony in culture media supplemented with 5% colloidal chitin and 1% skimmed milk.The LUM B001, B003, B013, B015 and B065-chitin strains presented higher quitinolytic and proteolytic activity,thereby having the potential for being evaluated in the biological control of phytopathogenic fungi. TheBacillus genus was found in cultivated and uncultivated soils; no statistical differences were found accordingto established crop (p <0.05); however, significant differences (p <0.05) were found between the areas beingstudied regarding the smaller amount of strains collected from land in the municipality of Tututepec, Oaxaca.

Genome-wide comparative analysis of the metalloprotease ftsH gene families between Arabidopsis thaliana and rice / 生物工程学报

Filamentation temperature-sensitive H (FtsH) is an ATP-dependent metalloprotease in prokaryotes and eukaryotes. Homology-based analysis was applied to determine 12 ftsH genes in Arabidopsis genome and 9 members in rice genome. Distribution of these ftsH genes on each chromosome displayed a clear preference for some chromosomes such as chromosome 1, 2, 5 of Arabidopsis and chromosome 1,5 of rice. All 21 FtsH proteins were subcellularly targeted to chloroplast or mitochondria. These members could be phylogenetically assorted as eight groups, of which no ortholog of AtFtsH12 in rice was detected. Paralogs in each group shared similarity higher than 80% and orthologs higher than 70%. This strongly indicated that the members from single group were descended from a common ancestral gene. Four pairs of paralogs, AtftsH1/5, AtftsH2/8, AtftsH7/9 and AftsH3/10 were found in Arabidopsis genome. However, only two pairs of ftsH paralogs, OsftsH3/8 and OsftsH4/5, resided in rice genome. The highly homologous members in each group performed striking conservation of exon-intron boundaries and preference for the variable residues in function domains. By contrast, there was significant difference in base composition and sequence length of introns. The comparative analysis of the ftsH gene families of Arabidopsis and rice provided the basis for characteristic and function research of ftsH genes in other plants.

Insertional Mutation of ftsH Gene in Streptococcus pneumoniae Causes Stress Sensitivities

FtsH is a membrane-bound, ATP-dependent protease involved in various cellular functions. To understand its roles in Streptococcus pneumoniae and host-pathogen interactions, we inactivated the ftsH gene of D39 strain by inserting a tetracycline-resistance (tet) gene. Several recombinants containing the tet cassette within the ftsH gene were confirmed by Western immunoblotting for the absence of pneumococcal FtsH protein that could cross-react with antiserum raised against Escherichia coli FtsH. Compared with the wild-type D39 strain, the ftsH null mutants grew slowly with encapsulation and alpha-hemolysis on blood agar plates, but failed to grow in liquid media other than Todd Hewitt yeast extract broth. Even fresh cultures of ftsH null mutants appeared gram-negative. When the incubation temperature of liquid cultures was shifted from 37degrees C to 40degrees C, the mutants gradually lysed, whereas the shift to 30degrees C abolished further growth. The mutants also exhibited increased sensitivity to salt and remarkable growth inhibition by optochin. These observations suggest that no functional FtsH protein in pneumococcal cells causes a loss of cell surface integrity, resulting in impairment of cell growth under normal and stressful conditions.

Insertional Mutation of ftsH Gene in Streptococcus pneumoniae Causes Stress Sensitivities

FtsH is a membrane-bound, ATP-dependent protease involved in various cellular functions. To understand its roles in Streptococcus pneumoniae and host-pathogen interactions, we inactivated the ftsH gene of D39 strain by inserting a tetracycline-resistance (tet) gene. Several recombinants containing the tet cassette within the ftsH gene were confirmed by Western immunoblotting for the absence of pneumococcal FtsH protein that could cross-react with antiserum raised against Escherichia coli FtsH. Compared with the wild-type D39 strain, the ftsH null mutants grew slowly with encapsulation and alpha-hemolysis on blood agar plates, but failed to grow in liquid media other than Todd Hewitt yeast extract broth. Even fresh cultures of ftsH null mutants appeared gram-negative. When the incubation temperature of liquid cultures was shifted from 37degrees C to 40degrees C, the mutants gradually lysed, whereas the shift to 30degrees C abolished further growth. The mutants also exhibited increased sensitivity to salt and remarkable growth inhibition by optochin. These observations suggest that no functional FtsH protein in pneumococcal cells causes a loss of cell surface integrity, resulting in impairment of cell growth under normal and stressful conditions.

Cloning and Nucleotide Sequence of Streptococcus pneumoniae ftsH Gene

The gene ftsH encodes a membrane-bound and ATP-dependent protease that is involved in a variety of cellular functions including heat-shock and stress response. Streptococcus pneumoniae DNA encompassing most part of the ftsH gene was cloned in Escherichia coli and sequenced. Due to the unsuccessful cloning as seen in other pneumococcal promoters, the 5'-end of the gene including the upstream promoter region was amplified by inverse polymerase chain reaction and then sequenced by cyclic sequencing. The amino acid sequence that is deduced from the 1,959 bp-long ftsH gene is very similar to FtsH of several gram-positive bacteria and E. coli within the region responsible for the AAA (ATPase associated with diverse cellular activities) function. Except for the N-terminal domain that contains a short extracellular region between two mernbrane-spanning segments, pneumococcal FtsH shows striking sequence similarity to that of a closely related species Lactococcus lactis within the conserved cytoplasmic domain where two ATP-binding motifs, the AAA Signature motif, and a zinc-binding motif are found.