Genes for ribitol and D-arabitol catabolism in Escherichia coli: their loci in C strains and absence in K-12 and B strains

Abstract

Escherichia coli C strains can grow at the expense of' the two natural pentitols ribitol and D-arabitol, sugar alcohols previously thought not to be utilized by E. coli. E. coli strains K-12 and B cannot utilize either compound. The genetic loci responsible for pentitol catabolism in E. coli C. designated rtl and atl, are separate and closely linked. Each lies between metG and his and is highly co-transducible with metG and with a P2 prophage attachment site. rtl and atl readily can be transduced into E. coli K-12 or B strains, in which they integrate at, or very near, their E. coli C location. Transduction also can be used to insert rtl and atl into certain E. coli K-12 F' plasmids. No recombination between E. coli C strains and either K-12 or B strains occurs within the rtl-atl genetic region after interstrain conjugations or transductions. No cryptic rtl or atl genes in K-12 or B strains can be detected by complementation, recombination, or mutagenesis. These results are consistent with the view that the rtl-atl portion of the E. coli C chromosome has no counterpart in E. coli K-12 or B and may have been obtained from an extrageneric source. Detailed biochemical and genetic comparisons of' pentitol utilization in E. coli and Klebsiella aerogenes are in progress. The ability to catabolize xylitol is conferred upon E. coli C strains by a mutation at or adjacent to the rtl locus, whereas in E. coli K-12 or B strains harboring rtl an additional mutation at a separate locus is required for xvlitol utilization.Ribitol, D-arabitol, L-arabitol. and xylitol are the four structurallv possible C5 polyol epimers. Ribitol and D-arabitol, the two that are found commonly in nature (6). can serve as the sole carbon and energy sources for natural strains of Aerobacter (59), Klebsiella (12, 13), Pseudomonas (50), Azotobacter (39), and yeast (1). Their metabolism, involving separate and inducible pathwavs, has been studied in considerable detail in A. aerogenes (2, 42. 55) and in K. aerogenes (12)(13)(14).

Molecular analysis of two fructokinases involved in sucrose metabolism of enteric bacteria

“…The genes can be transferred by P1 transduction from the chromosome of E. coli C to E. coti K-12 in which they replace the gat operon (Link and Reiner 1983;Woodward and Charles, 1983). They include (i) gene atlTior an active transport system which also transports D-mannitol in the free form (Lengeler, 1975b, and our unpublished results), (ii) gene atlA for an NAD*-dependent dehydrogenase which converts D-arabinitol to D-xylulose, and D-mannitol to D-fructose (Tanaka et ai, 1967), (iii) gene atlB for an ATPdependent xylulokinase which phosphorylates D-xylulose to D-xylulo 5-phosphate (Reiner, 1975), and (iv) gene atlR for a repressor specific for D-arabinitol. but not for D-mannitol (our unpublished results).…”

Construction of intergeneric hybrids using bacteriophage P1CM: transfer of the Klebsiella aerogenes ribitol dehydrogenase gene to Escherichia coli

“…We have shown that the ribitol dehydrogenase synthesized by these hybrids has the properties of the K. aerogenes enzyme and have mapped the rbtD gene at approximately 40 min on the E. coli chromosome. This map position is of interest as it corresponds very closely to the location of the newly described endogenous ribitol dehydrogenase gene in E. coli C strains (28).…”

“…Finally, the ability to work with E. coli enables us to ask whether the same evolutionary pathways are followed in two closely related organisms. In this regard it will be of particular interest to compare the initial properties and evolutionary patterns of the ribitol dehydrogenase from K. aerogenes with those of the enzyme from E. coli C (28). Preliminary experiments indicate that this newly described enzyme differs in several ways from the K. aerogenes ribitol dehydrogenase that we have characterized.…”

Acquisition of ability to utilize Xylitol: disadvantages of a constitutive catabolic pathway in Escherichia coli

“…Bacteriological and genetic techniques. Minimal and complex media have been described previously (16). Carbon and energy sources were 8 mM except where indicated.…”

“…CH is 5 g of casein hydrolysate (vitamin-free, Difco) per liter, supplemented with 15 g of agar per liter for plates. Growth of bacteria, the isolation of negative mutants, P1-mediated transduction, and conjugation are by standard procedures as previously described (16). Ribitol-constitutive derivatives were selected by their ability to utilize xylitol as sole carbon and energy source (25).…”