|
|
|
|
|
|
An Antimicrobial Peptide Is Produced by Extracellular Processing of a Protein from Propionibacterium jensenii. Therese Faye, 2002.A protease-activated antimicrobial peptide (PAMP) and its inactive precursor were purified from the culture supernatant of Propionibacterium jensenii LMG 3032 and characterized at the molecular level . PAMP is a 64-amino-acid cationic peptide of 6,383 Da with physicochemical features similar to those of bacteriocins from gram-positive bacteria . This peptide displayed bactericidal activity against several propionibacteria and lactobacilli . DNA sequencing indicated that the PAMP-encoding gene (pamA) is translated as a proprotein of 198 amino acids with an N-terminal signal peptide of 27 amino acids and that PAMP constitutes the C-terminal part of this precursor . The amino acid sequence of pro-PAMP showed no similarity to those of other known proteins . By using activity tests and mass spectrometry, we showed that PAMP was formed upon protease treatment of the precursor protein . The propionibacteria produced the PAMP precursor constitutively during growth up to a level of  4 mg/liter, but the producing bacteria were unable to activate the precursor . The requirement for an external protease represents a novel strategy for generating antimicrobial peptides .
Archaeal Homolog of Bacterial Type IV Prepilin Signal Peptidases with Broad Substrate Specificity. Sonja-Verena Albers, 2003. Two Paralogous Families of a Two-Gene Subtilisin Operon Are Widely Distributed in Oral Treponemes. Frederick F. Correia, 2003.Certain oral treponemes express a highly proteolytic phenotype and have been associated with periodontal diseases . The periodontal pathogen Treponema denticola produces dentilisin, a serine protease of the subtilisin family . The two-gene operon prcA-prtP is required for expression of active dentilisin (PrtP), a putative lipoprotein attached to the treponeme's outer membrane or sheath . The purpose of this study was to examine the diversity and structure of treponemal subtilisin-like proteases in order to better understand their distribution and function . The complete sequences of five prcA-prtP operons were determined for Treponema lecithinolyticum, "Treponema vincentii," and two canine species . Partial operon sequences were obtained for T . socranskii subsp . 04 as well as 450- to 1,000-base fragments of prtP genes from four additional treponeme strains . Phylogenetic analysis demonstrated that the sequences fall into two paralogous families . The first family includes the sequence from T . denticola. Treponemes possessing this operon family express chymotrypsin-like protease activity and can cleave the substrate N-succinyl-alanyl-alanyl-prolyl-phenylalanine-p-nitroanilide (SAAPFNA) . Treponemes possessing the second paralog family do not possess chymotrypsin-like activity or cleave SAAPFNA . Despite examination of a range of protein and peptide substrates, the specificity of the second protease family remains unknown . Each of the fully sequenced prcA and prtP genes contains a 5' hydrophobic leader sequence with a treponeme lipobox . The two paralogous families of treponeme subtilisins represent a new subgroup within the subtilisin family of proteases and are the only subtilisin lipoprotein family . The present study demonstrated that the subtilisin paralogs comprising a two-gene operon are widely distributed among treponemes . Specific Detection of Dehalococcoides Species by Fluorescence In Situ Hybridization with 16S rRNA-Targeted Oligonucleotide Probes. Yanru Yang, 2003.Dehalococcoides ethenogenes is the only known cultivated organism capable of complete dehalogenation of tetrachloroethene (PCE) to ethene . The prevalence of Dehalococcoides species in the environment and their association with complete dehalogenation of chloroethenes suggest that they play an important role in natural attenuation of chloroethenes and are promising candidates for engineered bioremediation of these contaminants . Both natural attenuation and bioremediation require reliable and sensitive methods to monitor the presence, distribution, and fate of the organisms of interest . Here we report the development of 16S rRNA-targeted oligonucleotide probes for Dehalococcoides species . The two designed probes together encompass 28 sequences of 16S rRNA genes retrieved from the public database . Except D . ethenogenes and CBDB1, all the others are environmental clones obtained from sites contaminated with chlorinated ethenes . They are all closely related and form a unique cluster of Dehalococcoides species . In situ hybridization of probe Dhe1259t with D . ethenogenes strain 195 and two enrichment cultures demonstrated the applicability of the probe to monitoring the abundance of active Dehalococcoides species in these enrichment samples .
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
