Open AccessThe gene encoding the alternative thymidylate synthase ThyX is regulated by sigma factor S ig B in C orynebacterium glutamicum ATCC 13032
Author(s) -
Cho Sukhyeong,
Yang Seokbin,
Rhie Hogun
Publication year - 2012
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2011.02494.x
Subject(s) - corynebacterium glutamicum , thymidylate synthase , mutant , microbiology and biotechnology , physics , biology , gene , biochemistry , genetics , fluorouracil , chemotherapy
Both ThyA and ThyX proteins catalyze the transfer of the methyl group from methylenetetrahydrofolate ( CH 2 H 4 ‐folate) to d UMP , forming d TMP . To estimate the relative steady state expression levels of ThyA and ThyX , W estern blot analysis was performed using ThyA or ThyX antiserum on total protein from the wild‐type, ΔthyX , and thyX ‐complemented strains of C orynebacterium glutamicum . The level of ThyA decreased gradually during the stationary growth phase but that of ThyX was maintained steadily. Whereas the expression level of ThyA in a ΔsigB strain was comparable to that of the wild‐type, the level of ThyX was significantly diminished in the deletion mutant and was restored to that of the wild‐type in the complemented strain, indicating that the level of ThyX was regulated by S ig B . Growth of the C . glutamicum ΔsigB strain was dependent upon coupling activity of dihydrofolate reductase ( DHFR ) with ThyA for the synthesis of thymidine, and thus showed sensitivity to the inhibition of DHFR by the experimental inhibitor, WR 99210‐ HCl . These results suggested that the relative levels of ThyA and ThyX differ in response to different growth phases and that S ig B is necessary for maintenance of the level of ThyX during transition into the stationary growth phase.