The Chlamydomonas reinhardtii MoCo carrier protein is multimeric and stabilizes molybdopterin cofactor in a molybdate charged form

FEBS Letters

Igeño, M.Isabel²  Witte, Claus-Peter²  Schwarz, Günter¹  Fernández, Emilio²  Mendel, Ralf¹ 

[1] Technische Universität Braunschweig, Botanisches Institut, Humboldstraße 1, D-38106 Braunschweig, Germany;Departamento de Bioquı́mica y Biologı́a Molecular, Avda. San Alberto Magno s/n, Facultad de Ciencias e Instituto Andaluz de Biotecnologı́a, Universidad de Córdoba, E-14071 Córdoba, Spain

关键词: Molybdenum cofactor;    Molybdopterin;    Tungstate;    Chlamydomonas reinhardtii;    CP;    carrier protein;    MoCo;    molybdenum cofactor;    MPT;    molybdopterin;    NR;    nitrate reductase;   

DOI  :  10.1016/S0014-5793(98)00756-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In Chlamydomonas reinhardtii, molybdopterin cofactor (MoCo) able to reconstitute active nitrate reductase (NR) with apoenzyme from the Neurospora crassa mutant nit-1 was found mostly bound to a carrier protein (CP). This protein is scarce in the algal free extracts and has been purified 520-fold. MoCoCP is a protein of 64 kDa with subunits of 16.5 kDa and an isoelectric point of 4.5. In contrast to free MoCo, MoCo bound to CP was remarkably protected against inactivation under both aerobic conditions and basic pH. MocoCP transferred active MoCo to apoNR in vitro without addition of molybdate, though reconstituted activity was 20% higher in the presence of molybdate. Incubation with tungstate specifically inhibited MoCoCP activity but had no effect on the activity of free MoCo released from milk xanthine oxidase. MoCoCP did not charge molybdate unless in the presence of N. crassa extracts. Our data support that MoCoCP stabilizes MoCo in an active form charged with molybdate to provide MoCo to apomolybdoenzymes.

【 授权许可】

Unknown