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A carboxyl-terminal Cys/His2-type zinc-finger motif in DNA primase influences DNA content in Synechococcus PCC 7942
被引:21
作者:
Bird, AJ
[1
]
Turner-Cavet, JS
[1
]
Lakey, JH
[1
]
Robinson, NJ
[1
]
机构:
[1] Univ Newcastle Upon Tyne, Sch Med, Dept Biochem & Genet, Newcastle Upon Tyne NE2 4HH, Tyne & Wear, England
关键词:
D O I:
10.1074/jbc.273.33.21246
中图分类号:
Q5 [生物化学];
Q7 [分子生物学];
学科分类号:
071010 ;
081704 ;
摘要:
The DNA primase gene, dnaG, has been isolated from the cyanobacterium Synechococcus PCC 7942, It is not part of a macromolecular synthesis operon but is cotranscribed with pheT and located adjacent to the metallothionein divergon, smt. At the carboxyl terminus of this DnaG is a Cys(2)/His(2) zinc-finger motif. The carboxyl-terminal 91 residues bound Zn-65 and 0.95 g atom of Zn2+ mol(-1) were detected with 4-(2-pyridylazo)resorcinol. Following exposure to Cd2+, 0.95 g atom of Cd2+ was displaced by 2 equivalents of p-(hydroxymercuri) phenylsulfonate mol(-1), while only 0.03 g atom of Cd2+ was displaced mol(-1) polypeptide missing the carboxyl-terminal (residue 592 onward) zinc-finger motif, Zn2+ caused an increase in intensity, and a reduction in wavelength, of Trp fluorescence at the tip of the predicted zinc-finger, while EDTA caused the converse. Cells containing a single chromosomal codon substitution (C597S), altering the zinc-finger, were generated by exploiting Zn2+-sensitive smt mutants and the proximity of dnaG to smt, Cells in which smt and dnaG(C597S) had integrated into the chromosome were selected via restored Zn2+ tolerance. Synechococcus PCC 7942 and its dnaG(C597S) mutant grew at equivalent rates, but the latter had a reduced number of chromosomes.
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页码:21246 / 21252
页数:7
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