Background Papers

Date:
1967-1980
Reference:
PP/CRI/H/6/13/6
Catalogue details

Licence: In copyright

Credit: Background Papers. Source: Wellcome Collection.

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    J. Mol. Evol. 12, 57-89 (1978) Journal of Molecular Evolution © by Springer-Verlag 1978 Multilocus Enzymes, Gene Regulation, and Genetic Sufficiency Emile Zuckerkandl* Linus Pauling Institute of Science and Medicine, 2700 Sand Hill Road, Menlo Park, California 94025, USA Summary. Moderately diverged small sets of nonallelic genes that control one type of protein, such as genes for isozymes, are usually considered to be present in order to permit adaptations of protein function to local conditions in orga- nismal time and space. However some irregularities, as well as some regularities, in the distribution of lactate dehydrogenase isozymes seem difficult to reconcile with this view. A complementary interpretation is based on selection for gene regulation. Irrespective of the relative importance of transcriptional control and of control through processing of the transcripts, regulatory patterns in higher organisms may be explored on the basis of formal relationships between mole cular components interacting within and between controller nodes. It is shown that an analysis in terms of controller node stability states may account for the variations in regulation of isozyme synthesis. Adaptive changes in regulatory sequences may insure the stability of the synthesis of a given type of protein in the face of developmental, as well as evolutionary, alterations in patterns of gene activity, correlated with the evolution of cell differentiation. It is proposed that gene duplication, beyond the addition of novel functions to the established ones, plays a further and rather opposite role. This role is to maintain the constancy of established protein functions in the presence of developmental and evolutionary change. To this effect the duplication of functional units of gene action, rather than merely of coding sequences, is likely to be required. In a certain number of cases, higher organisms can apparently dispense with a given moderately diverged set of genes and use a single gene instead. This fact is, to some extent, at variance with both the protein-functional and regulatory interpretations of the existence of the set. The relevance of the concept of genetic sufficiency is suggested as a solution, and possibilities offered by this concept for quantitative investigations in population genetics are outlined in an appendix. Increases in fitness occur automatically and perpetually regardless of ♦Directeur de Recherche, Centre National de la Recherche Scientifique, Paris, France. Reprint requests should be addressed to the Linus Pauling Institute 0022-2844/78/0012/0057/$ 06.60