Alfasi H, Friedberg D, Froedberg I
J Bacteriol. 1979 Jan;137(1):69-72. doi: 10.1128/jb.137.1.69-72.1979.
Two types of arsenate-resistant mutants of Micrococcus lysodeikticus were found: (i) mutants that grow in the presence of 10 mM but not 1 mM phosphate (Pi) with low uptake rate for Pi and arsenate, and (ii) mutants able to grow in the presence of 10 mM and 1 mM Pi, with a near-normal uptake rate for Pi but a low one for arsenate. The Km values for Pi transport and the Ki values for its competitive inhibition by arsenate were similar for the mutants and the wild type. Similar to the wild type, the mutants also accumulated Pi to high concentrations. In all strains, the transport of Pi was subject to repression by Pi. Mutant types showed lower Vmax but unaltered Km values for arsenate as compared to the wild type, and they accumulated arsenate to markedly lower levels. The results suggest a two-component transport system common to Pi and arsenate.
（i）在10 mM磷酸盐（Pi）存在下能生长，但在1 mM Pi存在下不能生长的突变体，其对Pi和砷酸盐的摄取率较低；（ii）在10 mM和1 mM Pi存在下都能生长的突变体，其对Pi的摄取率接近正常，但对砷酸盐的摄取率较低。突变体和野生型的Pi转运Km值以及砷酸盐对其竞争性抑制的Ki值相似。与野生型相似，突变体也能将Pi积累到高浓度。在所有菌株中，Pi的转运受到Pi的阻遏。与野生型相比，突变体类型的砷酸盐Vmax较低，但Km值未改变，并且它们积累的砷酸盐水平明显较低。结果表明Pi和砷酸盐存在一种双组分转运系统。
