Energy transduction anchors genes in organelles.
The work of mitochondria and chloroplasts is energy transduction in respiration and photosynthesis. The physico-chemical mechanisms of bioenergetics do not directly involve genes and heredity, and furthermore, redox chemistry is intrinsically mutagenic. Thus the small, functional genomes of mitochondria and chloroplasts are an oddity. Although extensively sequenced and catalogued, cytoplasmic genomes are still not explained. Genomic lethargy is not the answer. Some genes linger from the bacterial ancestors of these organelles, true, but most have left, and new ones arrive. There is a mounting case for a massive and indiscriminate intracellular gene transfer between organelles and the cell nucleus, with the frequency of relocation being comparable to that of mutation. Nevertheless, a few organellar proteins, all working at the core of bioenergetics, always seem to keep the genes encoding them close at hand. Stability amid flux suggests the invisible hand of selection. Selection for what? There are clues, and the beginnings of experimental support, for the theory that expression of mitochondrial and chloroplast genes is regulated by the function of their gene products. For safe and efficient energy transduction, genes in organelles are in the right place at the right time.
Allen
John F
JF
School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK. j.f.allen@qmul.ac.uk
Puthiyaveetil
Sujith
S
Ström
Jörgen
J
Allen
Carol A
CA
D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D019069:Cell Respiration / Q000502:physiology*; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D014644:Genetic Variation; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000502:physiology*
D024101:Mitochondrial Proteins