Disease relevance of clpX

• To elucidate the involvement of proteolysis in the regulation of stationary-phase adaptation, the clpA, clpX, and clpP protease mutants of Escherichia coli were subjected to proteome analysis during growth and during carbon starvation [1].
• Contrary to lambda plasmid replication, the efficiency of lytic growth of bacteriophage lambda was found to be dependent on the host growth rate in both wild-type bacteria and clpP and clpX mutants [2].
• In this study, we found that the FliC protein, a major component of flagellar filament, was overproduced in clpXP mutant EHEC, as previously reported for Salmonella [3].

High impact information on clpX

• The second 46,000-Da component was identified as ClpX (LopC), coded by a gene located in the same operon, but promoter distal to that coding for ClpP (Gottesman, S., Clark, W. P., de Crecy-Lagard, V., and Maurizi, M. R. (1993) J. Biol. Chem. 268, 22618-22626) [4].
• This turnover is dependent on the clpP and clpX genes [5].
• An open reading frame located upstream of the clpX gene was identified as the tig gene by similarity of its predicted product to other bacterial trigger factors [6].
• The gene order appears to be clpX lonS hupB, like the organization of the E. coli locus [7].
• An open reading frame homologous to the E. coli clpX gene was found in front of the lon gene [8].

Biological context of clpX

• Expression of different-size transcripts from the clpP-clpX operon of Escherichia coli during carbon deprivation [9].
• The cells carrying clpX alone on a multicopy plasmid successively produced the 46-kDa ClpX protein [10].
• This decision is influenced specifically by ClpP/ClpX-mediated O degradation and resultant inhibition of early lambda DNA replication because mutations in clpP and clpX genes have little effect on stability of other lambda proteins involved in the regulation of the phage developmental switch [11].
• Strong suppression of the conditional Rex[Ts] phenotype was imparted by ssrA and clpP (polar for clpX) null mutations, suggesting that RexA or RexB proteins made under conditions of polarity are subject to 10Sa RNA tagging and ClpXP degradation [12].

Associations of clpX with chemical compounds

• Lethality fixation did progress when protein synthesis was restricted and the cells were incubated in the presence of puromycin or were either clpP or clpX defective [13].

References