Gene expression changes in Corynebacterium glutamicum at increased growth temperature in the absence of PPIase FkpA

Comparative transcriptome analyses revealed 69 genes exhibiting ≥2-fold mRNA level changes in C. glutamicum DfkpA.Overall, 34 genes exhibited ≥2-fold increased and 35 genes at least 0.5-fold decreased mRNA levels in JVO1 DfkpA. About half of these genes (32) encode for hypothetical/putative proteins. LdhA encoding L-lactate dehydrogenase exhibited by far the strongest increased mRNA level (8.5-fold) in the absence of FkpA. Determination of the respective specific LdhA activities revealed about 2-fold increased activity in JVO1 DfkpA (0.73 ± 0.05 U/mg) compared to the reference JVO1 (0.41 ± 0.02 U/mg). Notably, the two short gene lists include four genes encoding transcriptional regulators exhibiting increased mRNA levels (farR, lexA, divS, znr) and two exhibiting decreased mRNA levels (ramB, mmpLR) in the absence of FkpA under the conditions tested. The mRNA level of cysK was increased (2.05-fold) which is repressed by RamB whose mRNA level was decreased (0.27-fold). In contrast, the mRNA level of RamB-repressed ald was decreased (0.31-fold) and not increased. To identify the influence of PPIase FkpA on global gene expression, DNA microarray analyses were performed with a ΔfkpA mutant compared to the reference C. glutamicum JVO1. For this purpose RNA was isolated from exponentially growing cells cultivated in CgXII minimal medium with 4% glucose at increased temperature (35°C) above growth optimum of C. glutamicum. Two biological replicates were performed with each representing an intra-array duplicate.