Scott C, Rawsthorne H, Upadhyay M, Shearman C A, Gasson M J, Guest J R, Green J
Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, UK.
FEMS Microbiol Lett. 2000 Nov 1;192(1):85-9. doi: 10.1111/j.1574-6968.2000.tb09363.x.
Lactococcus lactis ssp. cremoris MG1363 contains two FNR homologues, FlpA and FlpB, encoded by the distal genes of two paralogous operons (orfX(A/B)-orfY(A/B)-flpA/B). An flpA flpB double mutant strain is hypersensitive to hydrogen peroxide and has a depleted intracellular Zn(II) pool. The phenotypes of the flp mutant strains suggest that FlpA and FlpB control the expression of high and low affinity ATP-dependent Zn(II) uptake systems, respectively. Plate tests revealed that expression from a orfX(B)::lac reporter was activated by Cd(II), consistent with other Zn(II)-regulated systems. The link between a failure to acquire Zn(II) and hypersensitivity to oxidative stress suggests that Zn(II) may be required to protect vulnerable protein thiols from oxidation.
乳酸乳球菌乳脂亚种MG1363含有两个FNR同源物，FlpA和FlpB，由两个旁系同源操纵子（orfX(A/B)-orfY(A/B)-flpA/B）的远端基因编码。flpA flpB双突变菌株对过氧化氢高度敏感，且细胞内锌离子池耗尽。flp突变菌株的表型表明，FlpA和FlpB分别控制高亲和力和低亲和力的ATP依赖性锌离子摄取系统的表达。平板试验表明，orfX(B)::lac报告基因的表达受镉离子激活，这与其他锌离子调节系统一致。锌离子摄取失败与对氧化应激的超敏反应之间的联系表明，锌离子可能是保护易氧化的蛋白质巯基免受氧化所必需的。
