Mcp1 encodes the molybdenum cofactor carrier protein in Chlamydomonas reinhardtii and participates in protection, binding, and storage functions of the cofactor.
The molybdenum cofactor (Moco) is essential for the activity of all molybdoenzymes except nitrogenase. The cDNA for the Moco carrier protein (MocoCP) of Chlamydomonas reinhardtii has been cloned by reverse transcription PCR approaches with primers designed from microsequenced peptides of this protein. The C. reinhardtii MocoCP has been expressed in Escherichia coli. The recombinant protein has been purified to electrophoretic homogeneity and is found assembled into a homotetramer when Moco is not present under native conditions. Recombinant MocoCP has the same biochemical characteristics as MocoCP from C. reinhardtii, as it bound Moco from milk xanthine oxidase with high affinity, prevented Moco inactivation by oxygen, and transferred Moco efficiently to aponitrate reductase from the Neurospora crassa nit1 mutant. The genomic DNA sequence corresponding to the Chlamydomonas MocoCP gene, CrMcp1, also was isolated. This gene contained three introns in the coding region. The deduced amino acid sequence of CrMcp1 did not show a significant identity to functionally known proteins in the GenBank data base, although a significant conservation was found with bacterial proteins of unknown function. The results suggest that proteins having a Moco binding function probably exist in other organisms.
Ataya
Farid Shokry
FS
Departamento de Bioquimica y Biologia Molecular, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, Córdoba 14071, Spain.
Witte
Claus Peter
CP
Galván
Aurora
A
Igeño
María Isabel
MI
Fernández
Emilio
E
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D003067:Coenzymes; D018076:DNA, Complementary; D008667:Metalloproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D000090006:Molybdenum Cofactors; D011485:Protein Binding; D011621:Pteridines / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D002352:Carrier Proteins; D003067:Coenzymes; D018076:DNA, Complementary; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D011621:Pteridines; D011994:Recombinant Proteins; C022261:molybdopterin