title: A new type of metal-binding site in cobalt- and zinc-containing adenylate kinases isolated from sulfate-reducers Desulfovibrio gigas and Desulfovibrio desulfuricans ATCC 27774.
abstract: Adenylate kinase (AK) mediates the reversible transfer of phosphate groups between the adenylate nucleotides and contributes to the maintenance of their constant cellular level, necessary for energy metabolism and nucleic acid synthesis. The AK were purified from crude extracts of two sulfate-reducing bacteria (SRB), Desulfovibrio (D.) gigas NCIB 9332 and Desulfovibrio desulfuricans ATCC 27774, and biochemically and spectroscopically characterised in the native and fully cobalt- or zinc-substituted forms. These are the first reported adenylate kinases that bind either zinc or cobalt and are related to the subgroup of metal-containing AK found, in most cases, in Gram-positive bacteria. The electronic absorption spectrum is consistent with tetrahedral coordinated cobalt, predominantly via sulfur ligands, and is supported by EPR. The involvement of three cysteines in cobalt or zinc coordination was confirmed by chemical methods. Extended X-ray absorption fine structure (EXAFS) indicate that cobalt or zinc are bound by three cysteine residues and one histidine in the metal-binding site of the "LID" domain. The sequence 129Cys-X5-His-X15-Cys-X2-Cys of the AK from D. gigas is involved in metal coordination and represents a new type of binding motif that differs from other known zinc-binding sites of AK. Cobalt and zinc play a structural role in stabilizing the LID domain.
authors.affiliation: REQUIMTE, Departamento de Química, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Olga Yu
authors.initials: OY
authors.lastname: Gavel
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Bursakov
authors.forename: Giulia
authors.initials: G
authors.lastname: Di Rocco
authors.forename: José
authors.initials: J
authors.lastname: Trincão
authors.forename: Ingrid J
authors.initials: IJ
authors.lastname: Pickering
authors.forename: Graham N
authors.initials: GN
authors.lastname: George
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Calvete
authors.forename: Valery L
authors.initials: VL
authors.lastname: Shnyrov
authors.forename: Carlos D
authors.initials: CD
authors.lastname: Brondino
authors.forename: Alice S
authors.initials: AS
authors.lastname: Pereira
authors.forename: Jorge
authors.initials: J
authors.lastname: Lampreia
authors.forename: Pedro
authors.initials: P
authors.lastname: Tavares
authors.forename: José J G
authors.initials: JJ
authors.lastname: Moura
authors.forename: Isabel
authors.initials: I
authors.lastname: Moura
mesh_terms: D015502:Absorptiometry, Photon; D000263:Adenylate Kinase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D001051:Apoenzymes / Q000378:metabolism; D001665:Binding Sites; D003035:Cobalt / Q000737:chemistry*; D045285:Desulfovibrio desulfuricans / Q000201:enzymology*; D045286:Desulfovibrio gigas / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009994:Osmolar Concentration; D017434:Protein Structure, Tertiary; D011743:Pyrimidines; D016415:Sequence Alignment; D013056:Spectrophotometry, Ultraviolet; D015032:Zinc / Q000737:chemistry*
chemical_list: D001051:Apoenzymes; C097286:H 0294; D011743:Pyrimidines; D003035:Cobalt; D000263:Adenylate Kinase; D015032:Zinc