Comparison of three actin-coding sequences in the mouse; Evolutionary relationships between the actin genes of warm-blooded vertebrates
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We have determined the sequences of three recombinant cDNAs complementary to different mouse actin mRNAs that contain more than 90% of the coding sequences and complete or partial 3′ untranslated regions (3′UTRs): pAM 91, complementary to the actin mRNA expressed in adult skeletal muscle (αsk actin); pAF 81, complementary to an actin mRNA that is accumulated in fetal skeletal muscle and is the major transcript in adult cardiac muscle (αc actin); and pAL 41, identified as complementary to a β nonmuscle actin mRNA on the basis of its 3′UTR sequence. As in other species, the protein sequences of these isoforms are highly (>93%) conserved, but the three mRNAs show significant divergence (13.8–16.5%) at silent nucleotide positions in their coding regions. A nucleotide region located toward the 5′ end shows significantly less divergence (5.6–8.7%) among the three mouse actin mRNAs; a second region, near the 3′ end, also shows less divergence (6.9%), in this case between the mouse β and αsk actin mRNAs. We propose that recombinational events between actin sequences may have homogenized these regions. Such events distort the calculated evolutionary distances between sequences within a species. Codon usage in the three actin mRNAs is clearly different, and indicates that there is no strict relation between the tissue type, and hence the tRNA precursor pool, and codon usage in these and other muscle mRNAs examined. Analysis of codon usage in these coding sequences in different vertebrate species indicates two tendencies: increases in bias toward the use of G and C in the third codon position in paralogous comparisons (in the order αc), and in orthologous comparisons (in the order chicken < rodent < man). Comparison of actin-coding sequences between species was carried out using the Perler method of analysis. As one moves backward in time, changes at silent sites first accumulate rapidly, then begin to saturate after −(30–40) million years (MY), and actually decrease between −400 and −500 MY. Replacements or silent substitutions therefore cannot be used as evolutionary clocks for these sequences over long periods. Other phenomena, such as gene conversion or isochore compartmentalization, probably distort the estimated divergence time.
Key wordsActin-coding regions Sequence divergence Conversion Codon usage Evolution
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- Bagshaw CR (1982) Muscle contraction. In: Brammar WJ, Edidin M (eds) Outline studies in biology. Chapman and Hall, London New York, pp 30–38Google Scholar
- Buckingham ME, Minty AJ (1983) Contractile protein genes. In: Maclean N, Gregory SP, Flavell RA (eds) Eukaryotic genes: their structure, activity and regulation, vol 21. Butterworths, London, pp 365–395Google Scholar
- Davidson EH, Britten RJ (1973) Organization, transcription and regulation in the animal genome. Rev Biol 48:565–613Google Scholar
- McKenna MG (1969) The origin and early differentiation of therian mammals. Ann NY Acad Sci 167:217–240Google Scholar
- McKenna MG (1975) In: Luckett WP, Szalay FS (eds) Phylogeny of the primates. Plenum Press, New York, p 21Google Scholar
- Vandekerckhove J, De Couet HG, Weber K (1983) In: dos Remedios CG, Barden JA (eds) Actin: structure and function in muscle and non-muscle cells. Academic, Sydney, Australia, pp. 241–248Google Scholar
- Vandekerckhove J, Bugaisky G, Buckingham ME (1986) J Biol Chem, in pressGoogle Scholar
- Weydert A, Daubas P, Caravatti M, Minty AJ, Bugaisky G, Cohen A, Robert B, Buckingham ME (1983) Identification of a recombinant plasmid coding for an adult fast myosin heavy chain from mouse skeletal muscle: detection of a sequential accumulation of mRNAs encoding different myosin heavy chain isoforms during skeletal muscle development in vivo. J Biol Chem 258:13867–13874PubMedGoogle Scholar
- Weydert A, Daubas P, Lazaridis I, Barton P, Garner I, Leader DP, Bonhomme F, Catalan J, Simon D, Guénet JL, Gros F, Buckingham ME (1985) Genes for skeletal muscle myosin heavy chains are clustered and are not located on the same chromosome as a cardiac myosin heavy chain gene. Proc Natl Acad Sci USA 82: 7183–7187PubMedGoogle Scholar