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Mol Biol Evol. 2006 Mar;23(3):559-64. Epub 2005 Nov 9.

Tracing hybrid incompatibilities to single amino acid substitutions.

Author information

1
Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, USA. jsharrison@ucsd.edu

Abstract

Deleterious interactions among genes cause reductions in fitness of interpopulation hybrids (hybrid breakdown). Identifying genes involved in hybrid breakdown has proven difficult, and few studies have addressed the molecular basis of this widespread phenomenon. Because proper function of the mitochondrial electron transport system (ETS) requires a coadapted set of nuclear and mitochondrial gene products, ETS genes present an attractive system for studying the evolution of coadapted gene complexes within isolated populations and the loss of fitness in interpopulation hybrids. Here we show the effects of single amino acid substitutions in cytochrome c (CYC) on its functional interaction with another ETS protein, cytochrome c oxidase (COX) in the intertidal copepod Tigriopus californicus. The individual and pairwise consequences of three naturally occurring amino acid substitutions in CYC are examined by site-directed mutagenesis and found to differentially effect the rates of CYC oxidation by COX variants from different source populations. In one case, we show that interpopulation hybrid breakdown in COX activity can be attributed to a single naturally occurring amino acid substitution in CYC.

PMID:
16280539
DOI:
10.1093/molbev/msj058
[Indexed for MEDLINE]

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