期刊
BIOCHEMISTRY
卷 45, 期 51, 页码 15405-15410出版社
AMER CHEMICAL SOC
DOI: 10.1021/bi062026u
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资金
- NCRR NIH HHS [P41 RR003155-200117, P41 RR003155] Funding Source: Medline
- NHLBI NIH HHS [R01 HL016101-34, R01 HL016101, R37 HL016101, HL 16101, R01 HL016101-35, R01 HL016101-33] Funding Source: Medline
- NIGMS NIH HHS [R01 GM067193, GM 067193-04] Funding Source: Medline
In the respiratory chains of aerobic organisms, oxygen reductase members of the heme-copper superfamily couple the reduction of O-2 to proton pumping, generating an electrochemical gradient. There are three distinct families of heme-copper oxygen reductases: A, B, and C types. The A- and B-type oxygen reductases have an active-site tyrosine that forms a unique cross-linked histidine-tyrosine cofactor. In the C-type oxygen reductases (also called cbb(3) oxidases), an analogous active-site tyrosine has recently been predicted by molecular modeling to be located within a different transmembrane helix in comparison to the A- and B-type oxygen reductases. In this work, Fourier-transform mass spectrometry is used to show that the predicted tyrosine forms a histidine-tyrosine cross-linked cofactor in the active site of the C-type oxygen reductases. This is the first known example of the evolutionary migration of a post-translationally modified active-site residue. It also verifies the presence of a unique cofactor in all three families of proton-pumping respiratory oxidases, demonstrating that these enzymes likely share a common reaction mechanism and that the histidine-tyrosine cofactor may be a required component for proton pumping.
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