Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
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The PulO protein required for extracellular secretion of pullulanase by Klebsiella oxytoca is known to be highly homologous to two type IV prepilin peptidases, namely XcpA(PilD) (Pseudomonas aeruginosa) and TcpJ (Vibrio cholerae). The predicted prepilin peptidase activity of PulO was confirmed by showing that it could correctly process the product of the cloned pilE.1 type IV pilin structural gene from Neisseria gonorrhoeae in Escherichia coli. The P. aeruginosa prepilin peptidase and another putative prepilin peptidase, ComC from Bacillus subtilis, also processed prePilE. Subcellular fractionation showed that the pilE gene product that had been processed by PulO remained associated with the cytoplasmic membrane, as did the unprocessed precursor. PulO was also shown to process three of the four prePilE-PhoA hybrids tested. Southern hybridization experiments suggest that a pulO homologue is present in the N. gonorrhoeae chromosome.
Mol Microbiol 1992 Jul
PMID:PulO, a component of the pullulanase secretion pathway of Klebsiella oxytoca, correctly and efficiently processes gonococcal type IV prepilin in Escherichia coli. 135 33

The last gene (pulO) of the pulC-O pullulanase secretion gene operon of Klebsiella oxytoca codes for a protein that is 52% identical to the product of the pilD/xcpA gene required for extracellular protein secretion and type IV pilus biogenesis in Pseudomonas aeruginosa. The PilD/XcpA protein is known to remove the first six amino acids of the signal sequence of the type IV pilin precursor by cleaving after the glycine residue in the conserved sequence GF(M)XXXE (where X represents hydrophobic amino acids). This prepilin peptidase cleavage site is present in the products of four genes in the pulC-O operon (PulG, PulH, Pull and PulJ proteins). It is shown here that PulO processes the pulG gene product in vivo. Processing was maximal within 15 seconds, but experiments in which the expression of pulO was uncoupled from that of the other genes in the secretion operon suggest that processing can also occur post-translationally. The products of two pulG derivatives with internal inframe deletions were also processed by PulO, but the three PulG-PhoA hybrids, two PulJ-PhoA hybrids and the single PulH-PhoA hybrid tested did not appear to be processed. Sucrose gradient fraction experiments showed that both precursor and mature forms of PulG appear to be associated with low-density, outer membrane vesicles prepared by osmotic lysis of sphaeroplasts. Neither the xcpA gene nor the Bacillus subtilis gene comC, which is also homologous to pulO and codes for a protein with type IV prepilin peptidase activity, can correct the pullulanase secretion defect in an Escherichia coli strain carrying all of the genes required for secretion except pulO. Furthermore, neither XcpA nor ComC is able to process prePulG protein in vivo.
Mol Microbiol 1992 Mar
PMID:An enzyme with type IV prepilin peptidase activity is required to process components of the general extracellular protein secretion pathway of Klebsiella oxytoca. 157 4

ComGC is a cell surface-localized protein required for DNA binding during transformation in Bacillus subtilis. It resembles type IV prepilins in its N-terminal domain, particularly in the amino acid sequence surrounding the processing cleavage sites of these proteins. ComC is another protein required for DNA binding, which resembles the processing proteases that cleave type IV prepilins. We show here that ComGC is processed in competent cells and that this processing requires ComC. We also demonstrate that the PilD protein of Neisseria gonorrhoeae, a ComC homologue, can process ComGC in Escherichia coli, and that the ComC protein itself is the only B. subtilis protein needed to accomplish cleavage of ComGC in the latter organism. Based on NaOH-solubility studies, we have shown that in the absence of ComC, but in the presence of all other competence proteins, B. subtilis is incapable of correctly translocating ComGC to the outer face of the cell membrane. Finally, we show that ComGC can be cross-linked to yield a form with higher molecular mass, possibly a dimer, and present evidence suggesting that formation of the higher mass complex takes place in the membrane, prior to translocation. Formation of this complex does not require ComC or any of the comG products, other than ComGC itself.
Mol Microbiol 1995 Feb
PMID:ComC is required for the processing and translocation of comGC, a pilin-like competence protein of Bacillus subtilis. 778 24

Gene regB of bacteriophage T4 encodes a sequence-specific endoribonuclease that introduces cuts in early phage messenger RNAs. Cutting takes place specifically in the middle of the tetranucleotide GGAG, as soon as the first minute of infection. Out of the 20 processing sites so far identified, seven are in Shine-Dalgarno sequences. The others are localized in intercistronic regions or within coding sequences. In the latter case, cutting efficiency is much lower. regB-dependent cleavages can occur within AU-rich sequences downstream of processed GGAG motifs that are not in effective translation initiation sites. We looked for possible consequences of regB-dependent cuts on gene expression in two early regions of the T4 chromosome. In the comC alpha region, none of the three major RegB cleavage sites is in a Shine-Dalgarno sequence, and in the motA region the unique regB-dependent processing site is found within the Shine-Dalgarno sequence of the gene. We find that in the region of gene comC alpha, RegB decreases two- to threefold the chemical half-life of early transcripts, but does not change the functional half-life of mRNAs coding for protein ComC alpha. The amount of MotA protein synthesized by the wild-type is half that obtained in a regB mutant infection. We show that this is a direct consequence of mRNA processing by RegB at the Shine-Dalgarno sequence of motA. This regB-mediated translation inhibition is not accompanied by an important modification in motA mRNA chemical half-life. We show that rapid shut-off of MotA protein synthesis that occurs soon after infection results both from RegB processing within the translation initiation region of motA and from early transcription inhibition followed by regB-independent breakdown of the motA mRNA.
J Mol Biol 1993 Oct 05
PMID:Dual role of the sequence-specific bacteriophage T4 endoribonuclease RegB. mRNA inactivation and mRNA destabilization. 841 Nov 54