1cxy
From Proteopedia
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STRUCTURE AND CHARACTERIZATION OF ECTOTHIORHODOSPIRA VACUOLATA CYTOCHROME B558, A PROKARYOTIC HOMOLOGUE OF CYTOCHROME B5
Overview
A soluble cytochrome b(558) from the purple phototropic bacterium, Ectothiorhodospira vacuolata was completely sequenced by a combination of, automated Edman degradation and mass spectrometry. The protein, with a, measured mass of 10,094.7 Da, contains 90 residues and binds a single, protoheme. Unexpectedly, the sequence shows homology to eukaryotic, cytochromes b(5). As no prokaryotic homologue had been reported so far, we, developed a protocol for the expression, purification, and crystallization, of recombinant cytochrome b(558). The structure was solved by molecular, replacement to a resolution of 1.65 A. It shows that cytochrome b(558) is, indeed the first bacterial cytochrome b(5) to be characterized and differs, from its eukaryotic counterparts by the presence of a disulfide bridge and, a four-residue insertion in front of the sixth ligand (histidine)., Eukaryotes contain a variety of b(5) homologues, including soluble and, membrane-bound multifunctional proteins as well as multidomain enzymes, such as sulfite oxidase, fatty-acid desaturase, nitrate reductase, and, lactate dehydrogenase. A search of the Mycobacterium tuberculosis genome, showed that a previously unidentified gene encodes a fatty-acid desaturase, with an N-terminal b(5) domain. Thus, it may provide another example of a, bacterial b(5) homologue.
About this Structure
1CXY is a Single protein structure of sequence from Ectothiorhodospira shaposhnikovii with HEM as ligand. Full crystallographic information is available from OCA.
Reference
Structure and characterization of Ectothiorhodospira vacuolata cytochrome b(558), a prokaryotic homologue of cytochrome b(5)., Kostanjevecki V, Leys D, Van Driessche G, Meyer TE, Cusanovich MA, Fischer U, Guisez Y, Van Beeumen J, J Biol Chem. 1999 Dec 10;274(50):35614-20. PMID:10585439
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