Spontaneous mutation and DNa sequence evolution in the beta-ketoadipate pathway of Acinetobacter calcoaceticus
The bacterial chromosome replicates with such extraordinary faithfulness that nutritional traits, passed from generation to generation, can serve as a basis for bacterial taxonomy. Yet bacteria display extensive genetic plasticity in their ability to rapidly adapt to a change in their environment. T...
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| Format: | Thesis Electronic Book |
| Language: | English |
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1993
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| LEADER | 03736ntm a22003013 4500 | ||
|---|---|---|---|
| 001 | d4a5c9a5-230b-4630-aa95-24f52b1552c9 | ||
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| 008 | 110415s1993 xx |||||om||||||| ||eng d | ||
| 035 | |a (UMI)AAI9331313 | ||
| 035 | |a AAI9331313 | ||
| 040 | |a UMI |c UMI | ||
| 100 | 1 | |a Hartnett, Gail Beth | |
| 245 | 1 | 0 | |a Spontaneous mutation and DNa sequence evolution in the beta-ketoadipate pathway of Acinetobacter calcoaceticus |h [electronic resource] |
| 260 | |c 1993 | ||
| 300 | |a 1 online resource (166 p.) | ||
| 500 | |a Source: Dissertation Abstracts International, Volume: 54-06, Section: B, page: 2888 | ||
| 502 | |a Thesis (Ph.D.)--Yale University, 1993 | ||
| 506 | |a Access is restricted by licensing agreement | ||
| 520 | |a The bacterial chromosome replicates with such extraordinary faithfulness that nutritional traits, passed from generation to generation, can serve as a basis for bacterial taxonomy. Yet bacteria display extensive genetic plasticity in their ability to rapidly adapt to a change in their environment. This paradox is explored in this dissertation through molecular genetic studies of the $\beta$-ketoadipate pathway in a naturally transformable strain of Acinetobacter calcoaceticus. Chromosomal deletions introduced into the region of the pcaD gene (which codes for enol-lactone hydrolase) resulted in strains which failed to grow on succinate in the presence of p-hydroxybenzoate, presumably due to an accumulation of toxic metabolic intermediates. Under such conditions, these strains give rise to spontaneous mutants, which displayed wild type growth on the same media. This phenomenon was used to select for spontaneous mutation in the pobA and pcaHG genes, which code for p-hydroxybenzoate hydroxylase and protocatechuate 3,4-dioxygenase, respectively. The wild type pcaD region was reintroduced into the pobA mutants by transformation, followed by selection for growth with quinate as sole carbon source. Replacement of wild type pcaD into pcaHG mutants required introduction of a catD mutation into these strains. Selection for growth with benzoate as sole carbon source required a functional pcaD gene, introduced by transformation, and constitutively expressed due to endogenous accumulation of the inducer protocatechuate. Both pobA and pcaHG mutations were mapped by transformation using cloned DNA fragments as donors. The limits of the original deletions were defined by obtaining DNA sequence of a 2.75 kbp HindIII fragment which carried the complete pcaD gene. This sequence revealed the existence of an open reading frame of unknown function and led to a revision in the previously determined gene order within the operon. Comparison of the pcaD sequence with that of A. calcoaceticus catD confirmed earlier reports of extensive divergence between the two hydrolases, yet localized regions of sequence identity remain. Closer examination of the first 120 bases of pcaD showed patterns of oligonucleotide repeats, similar to those found in other genes for degradation of aromatics. A possible role is suggested for these repeated sequences in the generation of sequence diversity, and in maintainence of the evolved sequence | ||
| 590 | |a Access is available to the Yale community | ||
| 650 | 4 | |a Biology, Microbiology | |
| 650 | 4 | |a Biology, Molecular | |
| 710 | 2 | |a Yale University | |
| 773 | 0 | |t Dissertation Abstracts International |g 54-06B | |
| 791 | |a Ph.D | ||
| 792 | |a 1993 | ||
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| 999 | 1 | 1 | |l 9840344 |s ISIL:US-CTY |t BKS |a yulintx |c None |p UNLOANABLE |