Evolution of a Genetic Island of Catabolic Diversity in Bacteria

我们将扩大不动杆菌染色体片段的知识，该染色体片段允许细菌与来自环境的许多不同化学物质一起生长。目前测序和开放的遗传研究是pca-qui-pob簇包含基因相关的喹酸盐（qui）， shikimate （qui）和4-羟基苯甲酸盐（pob）通过原儿茶酸盐（pca）的分解代谢。pobA的下游是暂时命名为caf的基因，它是化学上类似的植物产物（咖啡酸盐、香豆酸盐和阿魏酸盐）通过产生原儿茶酸盐的代谢反应分解代谢所必需的。在DNA被克隆和排序之后，它将通过一个简单的程序进行遗传分析，该程序允许选择caf基因有缺陷的菌株。这些结果将扩大对分解咖啡酸盐、香豆酸盐和阿魏酸盐的酶的进化来源和生化机制的了解。这些酶很可能与脂肪酸氧化酶有共同的祖先。因此，进化和遗传研究的结合旨在阐明经典代谢序列的基因如何适应新的代谢挑战。氧化代谢主题的变异表现在catIJF和pcaIJF中，它们是通过基因转换交换序列信息的几乎相同的染色体片段。这种细胞内水平序列转移对不同不动杆菌细胞系中catIJF和pcaIJF协同分化的潜在贡献将与具有类似生化功能的caf基因的分化率进行比较。从上述研究中获得的知识将进一步定义分解代谢多样性的染色体岛，pca-qui-pob-caf基因簇包含遗传信息，允许不动杆菌在环境中与各种化合物一起生长。这些营养物质支持许多不动杆菌属的生长，但不是所有不动杆菌属的代表。我们将描述来自不同不动杆菌细胞系的pca-qui-pob-caf基因簇的遗传变异。特别注意将指向菌株表现出表型表明部分集群是缺席的。我们将确定缺失的表型特性在多大程度上反映了维持表型特性所需DNA的缺失。这一证据将表明，如果已知的表型变异是突变的遗传不连续性的结果，可能有助于区分不同的基因组物种的成员在复杂属不动杆菌。如果pca-qui-pob-caf簇的遗传变异与不动杆菌基因组种的生物分离符合其他标准，则有可能推断出该属内不同细胞系的进化如何受到环境中不同营养条件的影响。这个项目将扩展进化机制的知识，这导致了细菌从环境中去除化学物质的非凡能力。这种知识的应用可以改善环境化学品的生物清理，也可以帮助开发将自然资源转化为对社会有更高价值的化学品的细菌过程。

Ornston 9603980 We shall expand knowledge of an Acinetobacter chromosomal segment that allows growth of the bacteria with many different chemicals from the environment. Presently sequenced and open to genetic investigation is the pca-qui-pob cluster containing genes associated with catabolism of quinate (qui), shikimate (qui) and 4-hydroxybenzoate (pob) through protocatechuate (pca). Downstream from pobA are genes provisionally designated caf and required for catabolism of chemically analogous plant products (caffeate, coumarate and ferulate) through metabolic reactions that give rise to protocatechuate. After this DNA has been cloned and sequenced, it will be subjected to genetic analysis by a simple procedure that allows selection of strains in which caf genes are defective. The results will expand knowledge of both the evolutionary source and the biochemical mechanisms of enzymes that catabolize caffeate, coumarate and ferulate. The enzymes are likely to share ancestry with enzymes associated with the (-oxidation of fatty acids. Thus the combination of evolutionary and genetic investigations is designed to elucidate how genes for a classical metabolic sequence have been adapted to novel metabolic challenges. Variations upon the metabolic theme of ( oxidation are represented in catIJF and pcaIJF, nearly identical chromosomal segments that exchange sequence information by gene conversion. The potential contribution of this intracellular horizontal sequence transfer to concerted divergence of catIJF and pcaIJF in divergent Acinetobacter cell lines will be compared with the rates of divergence of caf genes with analogous biochemical functions. Knowledge emerging from the foregoing studies will define further a chromosomal island of catabolic diversity, the pca-qui-pob-caf gene cluster containing genetic information allowing growth of Acinetobacter with a wide range of compounds in the environment. The nutrients support the growth of many but not all representatives of the genus Acinetobacte r. We shall characterize genetic variants of the pca-qui-pob-caf gene cluster from different Acinetobacter cell lines. Particular attention will be directed to strains exhibiting phenotypes indicating that portions of the cluster are absent. We shall determine the extent to which the missing phenotypic properties reflect the absence of DNA required for their maintenance. This evidence will indicate if the known phenotypic variations are the consequence of abrupt genetic discontinuities that may help to distinguish members of different genomospecies within the complex genus Acinetobacter. If genetic variations in the pca-qui-pob-caf cluster are concordant with biological separation of Acinetobacter genomospecies by other criteria, it may be possible to infer how evolution of different cell lines within the genus was influenced by different sets of nutritional opportunities within the environment. This project will expand knowledge of evolutionary mechanisms that led to the extraordinary ability of bacteria to remove chemicals from the environment. Application of such knowledge may improve the biological cleanup of environmental chemicals and also may assist in development of processes for bacterial conversion of natural resources to chemicals with improved value for society.