Surgey N, Robert-Baudouy J, Condemine G
Laboratoire de Génétique Moléculaire des Microorganismes, Unité Recherche Associée, Villeurbanne, France.
J Bacteriol. 1996 Mar;178(6):1593-9. doi: 10.1128/jb.178.6.1593-1599.1996.
A new type of Erwinia chrysanthemi mutant displaying a derepressed synthesis of pectate lyase was isolated. The gene mutated in these strains, pecT, encodes a 316-amino-acid protein with a size of 34,761 Da that belongs to the LysR family of transcriptional activators and presents 61% identity with the E. coli protein LrhA. PecT represses the expression of pectate lyase genes pelC, pelD, pelE, pelL, and kdgC, activates pelB, and has no effect on the expression of pelA or the pectin methylesterase genes pemA and pemB. PecT activiates its own expression. The mechanism by which PecT regulates pectate lyase synthesis is independent of that of the two characterized regulators of pectate lyase genes, KdgR and PecS. In contrast to most of the members of the LysR family, pecT is not transcribed in a direction opposite that of a gene that it regulates. pecT mutants are mucoid when grown on minimal medium plates and flocculate when grown in liquid minimal medium, unless leucine or alanine is added to the medium. Thus, pecT may regulate other functions in the bacterium.
分离出了一种新型的菊欧文氏菌突变体，该突变体表现出果胶酸裂解酶的去阻遏合成。这些菌株中发生突变的基因pecT编码一种316个氨基酸的蛋白质，大小为34,761 Da，属于转录激活因子的LysR家族，与大肠杆菌蛋白LrhA有61%的同源性。PecT抑制果胶酸裂解酶基因pelC、pelD、pelE、pelL和kdgC的表达，激活pelB，对pelA或果胶甲酯酶基因pemA和pemB的表达没有影响。PecT激活其自身的表达。PecT调节果胶酸裂解酶合成的机制独立于果胶酸裂解酶基因的两个已鉴定的调节因子KdgR和PecS。与LysR家族的大多数成员不同，pecT的转录方向与其调节的基因的转录方向不相反。pecT突变体在基本培养基平板上生长时呈黏液状，在液体基本培养基中生长时会絮凝，除非在培养基中添加亮氨酸或丙氨酸。因此，pecT可能调节该细菌中的其他功能。
