The catabolic pathways of microorganisms are essential for completion of cycles of matter in the environment and the best hope for reclamation of polluted areas. The processes that underlie catabolic evolution are poorly understood. Presumably central events are (i) creation of copies of DNA sequences encoding highly evolved protein structures; (ii) selection of protein functions associated with a novel metabolic process; (iii) modification of DNA sequences so that the protein functions achieve enhanced efficiency. The most obvious protein functions are ligand binding and the catalytic activity of enzymes, but equally important are amino acid sequences associated with protomer-protomer association in oligomeric enzymes and, possibly, the association of different proteins in aggregates of enzymes that catalyze consecutive metabolic reactions. Little is known about the amino acid sequences associated with functions of catabolic enzymes, and it is this gap in knowledge that the research program is designed to fill. The subject of the research is the Beta-ketoadipate pathway, a widely distributed mechanism for utilization of aromatic and hydroaromatic growth substrates. Metabolic reactions included in the study are quite different: cycloisomerization, intralactonic migration of a double bond, lactone hydrolysis, acyl-CoA transfer, and thiolytic cleavage. The available evidence suggests that the enzymes catalyzing respective steps in the pathways are members of enzyme families, groups of divergent enzymes that subject different substrates to similar catalytic reactions. This proposition will be explored by using chemical and genetic techniques to identify amino acid sequences associated with catalytic activity and substrate binding; the results of this study should establish a basis for establishing relationships among enzymes that catalyze similar reactions. By understanding what was selected in metabolic evolution, the amino acid sequences associated with specific functions, we may hope to design rational procedure for directing and accelerating the process.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM033377-02
Application #
3283050
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1984-08-01
Project End
1989-07-31
Budget Start
1985-08-01
Budget End
1986-07-31
Support Year
2
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Yale University
Department
Type
Schools of Arts and Sciences
DUNS #
082359691
City
New Haven
State
CT
Country
United States
Zip Code
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Frantz, B; Ngai, K L; Chatterjee, D K et al. (1987) Nucleotide sequence and expression of clcD, a plasmid-borne dienelactone hydrolase gene from Pseudomonas sp. strain B13. J Bacteriol 169:704-9
Ngai, K L; Schlomann, M; Knackmuss, H J et al. (1987) Dienelactone hydrolase from Pseudomonas sp. strain B13. J Bacteriol 169:699-703
Neidle, E L; Ornston, L N (1987) Benzoate and muconate, structurally dissimilar metabolites, induce expression of catA in Acinetobacter calcoaceticus. J Bacteriol 169:414-5
Doten, R C; Ngai, K L; Mitchell, D J et al. (1987) Cloning and genetic organization of the pca gene cluster from Acinetobacter calcoaceticus. J Bacteriol 169:3168-74

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