Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proteasome-like ClpP protease is widely distributed and structurally conserved among bacteria and eukaryotic cell organelles. In Chlamydomonas eugametos, however, the chloroplast clpP gene predicted a much larger ClpP protein containing large insertion sequences (ISs). One insertion sequence, IS2, is 456 amino acid residues long and not similar to known proteins. Here we show that IS2 is an unusual intein, and its protein splicing activity in Escherichia coli cells can be activated by a single amino acid substitution. Analysis of IS2 sequence revealed short sequence motifs that are similar to known intein motifs, including putative LAGLI-DADG endonuclease motifs. But a histidine residue conserved at the C terminus of known inteins is replaced in the IS2 sequence by a glycine residue (Gly455), rendering the IS2 sequence incapable of detectable protein splicing when tested in E. coli cells. Changing Gly455 to histidine activated the ability of IS2 to undergo protein splicing in E. coli cells. The IS2 sequence (intein) was precisely excised from a precursor protein, with the flanking sequences (exteins) joined together by a normal peptide bond.
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PMID:Identification of an unusual intein in chloroplast ClpP protease of Chlamydomonas eugametos. 911 46

Efficient acquisition of genes that encode a restriction and modification (R-M) system with specificities different from any already present in the recipient bacterium requires the sequential production of the new modification enzyme followed by the restriction activity in order that the chromosome of the recipient bacterium is protected against attack by the restriction endonuclease. We show that ClpX and ClpP, the components of ClpXP protease, are necessary for the efficient transmission of the genes encoding EcoKI and EcoAI, representatives of two families of type I R-M systems, thus implicating ClpXP in the modulation of restriction activity. Loss of ClpX imposed a bigger barrier than loss of ClpP, consistent with a dual role for ClpX, possibly as a chaperone and as a component of the ClpXP protease. Transmission of genes specifying EcoKI was more dependent on ClpX and ClpP than transmission of the genes for EcoAI. Sensitivity to absence of the protease was also influenced by the mode of gene transfer; conjugative transfer and transformation were more dependent on ClpXP than transduction. In the absence of either ClpX or ClpP transfer of the EcoKI genes by P1-mediated transduction was impaired, transfer of the EcoAI genes was not.
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PMID:ClpX and ClpP are essential for the efficient acquisition of genes specifying type IA and IB restriction systems. 959 94