Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.3 (RNase III)
 1,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The TnphoA-induced Bradyrhizobium japonicum mutant 184 shows slow growth and aberrant colonization of soybean nodules. Using a DNA fragment adjacent to the transposon insertion site as a probe, a 3.4-kb BglII fragment of B. japonicum 110spc4 DNA was identified and cloned. Sequence analysis indicated that two truncated ORFs and three complete ORFs were encoded on this fragment. A database search revealed homologies to several other prokaryotic proteins: PdxJ (an enzyme involved in vitamin B6 biosynthesis), AcpS (acyl carrier protein synthase), Lep or Sip (prokaryotic type I signal peptidase), RNase III (an endoribonuclease which processes double-stranded rRNA precursors and mRNA) and Era (a GTP-binding protein required for cell division). The mutation in strain 184 was found to lie within the signal peptidase gene, which was designated sipF. Therefore, sipF is located in a region that encodes gene products involved in posttranscriptional and posttranslational processing processes. By complementation of the lep(ts) E. coli mutant strain IT41 it was demonstrated that sipF indeed encodes a functional signal peptidase, and genetic complementation of B. japonicum mutant 184 by a 2.8-kb SalI fragment indicated that sipF is expressed from a promoter located directly upstream of sipF. Using a non-polar kanamycin resistance cassette, a specific sipF mutant was constructed which exhibited defects in symbiosis similar to those of the original mutant 184.
 ...
PMID:A second gene for type I signal peptidase in Bradyrhizobium japonicum, sipF, is located near genes involved in RNA processing and cell division. 987 Jun 99

The type I signal peptidase lepB genes from Rickettsia rickettsii and Rickettsia typhi, the etiologic agents of Rocky Mountain spotted fever and murine typhus, respectively, were cloned and characterized. Sequence analysis of the cloned lepB genes from R. rickettsii and R. typhi shows open reading frames of 801 and 795 nucleotides, respectively. Alignment analysis of the deduced amino acid sequences reveals the presence of highly conserved motifs that are important for the catalytic activity of bacterial type I signal peptidase. Reverse transcription-PCR and Northern blot analysis demonstrated that the lepB gene of R. rickettsii is cotranscribed in a polycistronic message with the putative nuoF (encoding NADH dehydrogenase I chain F), secF (encoding protein export membrane protein), and rnc (encoding RNase III) genes in a secF-nuoF-lepB-rnc cluster. The cloned lepB genes from R. rickettsii and R. typhi have been demonstrated to possess signal peptidase I activity in Escherichia coli preprotein processing in vivo by complementation assay.
 ...
PMID:Molecular and functional analysis of the lepB gene, encoding a type I signal peptidase from Rickettsia rickettsii and Rickettsia typhi. 1286 68

Legionella pneumophila is a facultative intracellular Gram-negative rod-shaped bacterium that has become an important cause of both community-acquired and nosocomial pneumonia. Numerous studies concerning the unravelling of the virulence mechanism of this important pathogen have been initiated. As evidence is now accumulating for the involvement of protein secretion systems in bacterial virulence in general, the type I signal peptidase (LepB) of L. pneumophila was of particular interest. This endopeptidase plays an essential role in the processing of preproteins carrying a typical amino-terminal signal peptide, upon translocation across the cytoplasmic membrane. This paper reports the cloning and the transcriptional analysis of the L. pneumophila lepB gene encoding the type I signal peptidase (SPase). Reverse transcription PCR experiments showed clear lepB expression when L. pneumophila was grown both in culture medium, and also intracellularly in Acanthamoeba castellanii, a natural eukaryotic host of L. pneumophila. In addition, LepB was shown to be encoded by a polycistronic mRNA transcript together with two other proteins, i.e. a LepA homologue and a ribonuclease III homologue. SPase activity of the LepB protein was demonstrated by in vivo complementation analysis in a temperature-sensitive Escherichia coli lepB mutant. Protein sequence and predicted membrane topology were compared to those of leader peptidases of other Gram-negative human pathogens. Most strikingly, a strictly conserved methionine residue in the substrate binding pocket was replaced by a leucine residue, which might influence substrate recognition. Finally it was shown by in vivo experiments that L. pneumophila LepB is a target for (5S,6S)-6-[(R)-acetoxyethyl]-penem-3-carboxylate, a specific inhibitor of type I SPases.
 ...
PMID:Molecular and functional characterization of type I signal peptidase from Legionella pneumophila. 1513 9