evolutionary relationships among a set of genes which have coevolved within a single cell line
	Nicholas Ornston, Ph.D. Professor Emeritus Email: nicholas.ornston@yale.edu Room: KBT 752 Phone: (203) 432-3498 B.A. Harvard College 1961; Ph.D. University of California, Berkeley 1965

It is appropriate for biologists to ask why bacteria are interesting, and the answer lies in evolutionary challenges presented by the dimensions of these smallest of creatures. Limits in both size and information demand that each bacterium be a specialist. Collectively, these specialists have occupied a range of niches representing the extremes of opportunities for life. Specialists cannot not survive alone, so it follows that bacteria live in consortia. A further key to the success of the organisms is their ability to network both physiologically and genetically. Thus appreciation of the skills inherent in bacterial survival primes enthusiastic interest in the interplay of forces that drive life in both its elegant simplicity and its full complexity. Exploration of the life of bacteria requires a native guide, and our investigations are aided by a bacterial strain that exhibits extraordinary competence for natural transformation: donor DNA, provided as cell lysate, restriction fragment or polymerase chain reaction product, is readily assimilated into the chromosome of several percent of the cells in a recipient population. The ease of genetic manipulation removes barriers between genotype and pheno-type. It is relatively simple to determine the function of a DNA fragment, and strains in which such chromosomal segment has been experimentally altered are easily obtained. The laboratory strain is a representative of the genus Acinetobacter, a widely divergent group of organisms that are abundant occupants of our planet. We have developed procedures for recovering genes from natural isolates in the laboratory strain, and this fosters our ambition to bridge the gap between our understanding of evolution (mutation and selection in the natural environment) and the observed genetic malleability of organisms in the laboratory.

Our findings suggest that novel mutations may be selected under certain conditions, and our present research is directed largely to the elucidation of genetic mechanisms that underlie both modification of DNA by mutation and the shuffling of DNA into new genetic combinations. It should be noted that crystal structures have been determined for a number of the enzymes under investigation, so selective forces can be traced at levels ranging from atomic distances to natural populations of organisms. In a related study, we investigate membrane proteins asso-ciated with transport. The proteins are inducible, and their biosynthetic regulation indicates that their evolu-tionary history is shared with the sets of enzymes that we have examined. We analyze structural and functional relationships between the membrane proteins, the enzymes, and the genes that govern their expression.

Selected Publications

Kok, R. G., D. M. Young, and L. N. Ornston. 1999. Phenotypic expression of PCR-generated random mutations in a Pseudomonas putida gene after its introduction into an Acinetobacter chromosome by natural transformation. Appl. Env. Microbiol. 65: 1675-1680.

A. Segura, P. V. Bünz, D. A. D'Argenio, and L. N. Ornston. 1999. Genetic analysis of a chromosomal region containing vanA and -B, genes required for conversion of either ferulate or vanillate to protoca-techuate in Acinetobacter. J. Bacteriol. 181:3494-3504.

D. A. D'Argenio, A. Segura, W. M. Coco, P. V. Bünz, and L. N. Ornston. 1999. The physiological contribution of Acinetobacter PcaK, a transport system that acts upon protoca-techuate, can be masked by the overlapping specificity of VanK. J. Bacteriol. 181:3505-3515

D'Argenio, D.A., M. W. Vetting, D. H. Ohlendorf, and L. N. Ornston. 1999. Substitution, insertion, deletion, suppression, and altered substrate-specificity in functional protoca-techuate 3,4-dioxygenases. J. Bacteriol. 181:6478-6487. is a mechano-chemically active motor and a GAP for rho. J. Cell Sci. 111(7): 941-950.

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