Molecular recognition between Azotobacter vinelandii rhodanese and a sulfur acceptor protein.
The occurrence of rhodanese-like proteins in the major evolutionary phyla, together with the observed abundance of these proteins also within the same genome, suggests that their function cannot be limited to cyanide scavenging. The aim of the present study was to investigate whether Azotobacter vinelandii RhdA, an enzyme possessing unique biochemical and structural features with respect to other members of rhodanese homology superfamily, could recognize a suitable protein as a potential acceptor of the sulfane sulfur held on its catalytic Cys residue. Both the potential sulfur-delivery RhdA-S and the sulfur-deprived RhdA were found to interact with either holo- or apo-adrenodoxin, the 'substrate' protein used in this work. Interaction of RhdA-S with apo-adrenodoxin led to mobilization of RhdA-S sulfane sulfur. Under appropriate conditions, the sulfur released from RhdA-S was productively used for 2Fe-2S cluster reconstitution to yield holo-adrenodoxin from apo-adrenodoxin in the absence of any other sulfur source. A comparison of the reactivity of RhdA-S with protein and non-protein thiols allowed also some insights into the accessibility of the sulfane sulfur carried by RhdA.
Cereda
Angelo
A
Dipartimento di Scienze Molecolari Agroalimentari, Università di Milano, I-20133 Milano, Italy.
Forlani
Fabio
F
Iametti
Stefania
S
Bernhardt
Rita
R
Ferranti
Pasquale
P
Picariello
Gianluca
G
Pagani
Silvia
S
Bonomi
Francesco
F
D000325:Adrenodoxin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001059:Apoproteins / Q000737:chemistry / Q000378:metabolism; D016948:Azotobacter vinelandii / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D015153:Blotting, Western; D020134:Catalytic Domain; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000737:chemistry; D013058:Mass Spectrometry; D017510:Protein Folding; D013050:Spectrometry, Fluorescence; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry* / Q000378:metabolism; D013466:Sulfurtransferases / Q000737:chemistry / Q000378:metabolism; D013884:Thiosulfate Sulfurtransferase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
D001059:Apoproteins; D013438:Sulfhydryl Compounds; D000325:Adrenodoxin; D013455:Sulfur; D007501:Iron; D013466:Sulfurtransferases; C063506:sulfane sulfurtransferase; D013884:Thiosulfate Sulfurtransferase; D003545:Cysteine