Y. Shirai et al., SUPPRESSION OF FTSH MUTANT PHENOTYPES BY OVERPRODUCTION OF MOLECULAR CHAPERONES, Journal of bacteriology, 178(4), 1996, pp. 1141-1145
Decreased intracellular levels of FtsH, a membrane-bound ATPase, led t
o retardation of growth and protein export, as well as to an abnormal
translocation of alkaline phosphatase that had been attached to a cyto
plasmic domain of a multispanning membrane protein, SecY. The last phe
notype is designated Std (stop transfer defective). In this study, we
examined the effects of overproduction of some molecular chaperones on
the phenotypes of ftsH mutants. The growth retardation was partially
suppressed by overproduction of GroEL/GroES (Hsp60/Hsp10) or HtpG (Hsp
90), although these chaperones could not totally substitute for FtsH.
Overproduction of HtpG specifically alleviated the Std phenotype, whil
e that of GroEL/GroES alleviated the protein export defect of ftsH mut
ants. These results suggest that FtsH functions can be somehow compens
ated for when the cellular concentrations of some molecular chaperones
increase.