The rhodanese RhdA helps Azotobacter vinelandii in maintaining cellular redox balance.
The tandem domain rhodanese-homology protein RhdA of Azotobacter vinelandii shows an active-site loop structure that confers structural peculiarity in the environment of its catalytic cysteine residue. The in vivo effects of the lack of RhdA were investigated using an A. vinelandii mutant strain (MV474) in which the rhdA gene was disrupted by deletion. Here, by combining analytical measurements and transcript profiles, we show that deletion of the rhdA gene generates an oxidative stress condition to which A. vinelandii responds by activating defensive mechanisms. In conditions of growth in the presence of the superoxide generator phenazine methosulfate, a stressor-dependent induction of rhdA gene expression was observed, thus highlighting that RhdA is important for A. vinelandii to sustain oxidative stress. The potential of RhdA to buffer general levels of oxidants in A. vinelandii cells via redox reactions involving its cysteine thiol is discussed.
Remelli
William
W
Dipartimento di Scienze Molecolari Agroalimentari, Università degli Studi di Milano, I-20133 Milano, Italy.
Cereda
Angelo
A
Papenbrock
Jutta
J
Forlani
Fabio
F
Pagani
Silvia
S
D016948:Azotobacter vinelandii / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D003545:Cysteine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011487:Protein Conformation; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism; D013884:Thiosulfate Sulfurtransferase / Q000737:chemistry / Q000378:metabolism*
D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; C545158:cysteine thiolate; D013884:Thiosulfate Sulfurtransferase; D003545:Cysteine