Regulation of ppk expression and in vivo function of Ppk in Streptomyces lividans TK24.
The ppk gene of Streptomyces lividans encodes an enzyme catalyzing, in vitro, the reversible polymerization of the gamma phosphate of ATP into polyphosphate and was previously shown to play a negative role in the control of antibiotic biosynthesis (H. Chouayekh and M. J. Virolle, Mol. Microbiol. 43:919-930, 2002). In the present work, some regulatory features of the expression of ppk were established and the polyphosphate content of S. lividans TK24 and the ppk mutant was determined. In Pi sufficiency, the expression of ppk was shown to be low but detectable. DNA gel shift experiments suggested that ppk expression might be controlled by a repressor using ATP as a corepressor. Under these conditions, short acid-soluble polyphosphates accumulated upon entry into the stationary phase in the wild-type strain but not in the ppk mutant strain. The expression of ppk under Pi-limiting conditions was shown to be much higher than that under Pi-sufficient conditions and was under positive control of the two-component system PhoR/PhoP. Under these conditions, the polyphosphate content of the cell was low and polyphosphates were reproducibly found to be longer and more abundant in the ppk mutant strain than in the wild-type strain, suggesting that Ppk might act as a nucleoside diphosphate kinase. In light of our results, a novel view of the role of this enzyme in the regulation of antibiotic biosynthesis in S. lividans TK24 is proposed.
Ghorbel
Sofiane
S
Department of Microbiology, Immunology and Molecular Genetics, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, USA.
Smirnov
Aleksey
A
Chouayekh
Hichem
H
Sperandio
Brice
B
Esnault
Catherine
C
Kormanec
Jan
J
Virolle
Marie-Joelle
MJ
D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D018387:Codon, Initiator; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D010710:Phosphates; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics* / Q000378:metabolism*; D011122:Polyphosphates / Q000032:analysis / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D048170:Streptomyces lividans / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development
D001426:Bacterial Proteins; D018387:Codon, Initiator; D003470:Culture Media; D010710:Phosphates; D011122:Polyphosphates; D000255:Adenosine Triphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor)