Metabolic Acquisitions Through Laboratory Selection

Mortlock, Robert P.

doi:10.1146/annurev.mi.36.100182.001355

Cited by 57 publications

(19 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Many members of the Enterobacteriaceae have been found to acquire new metabolic functions by mutations that allow the enzymes of different pathways to be used for new functions (17). Two types of mutations have been discovered.…”

Section: Downloaded Frommentioning

confidence: 99%

Lactose and melibiose metabolism in Erwinia chrysanthemi

Gray¹,

Lindner²,

Brand³

et al. 1986

J Bacteriol

View full text Add to dashboard Cite

A Lac' mutant of Erwinia chrysanthemi was isolated from the Lac-wild type on lactose agar. (3-Galactosidase was expressed independently of lactose transport in both the mutant and the wild type, and neither strain expressed thiogalactoside transacetylase. Lactose transport and a-galactosidase, constitutive in the Lac' strain, were coordinately induced in the Lac-strain by melibiose and raffinose but not by isopropyl-,B-D-thiogalactopyranoside or thiomethyl-3-D-galactopyranoside. Melibiose was a strong inhibitor of both the melibiose-and the raffinose-induced lactose permeases, whereas raffinose was a strong inhibitor of only the raffinose-induced lactose permease.Many members of the family Enterobacteriaceae possess operons that code for enzymes involved in lactose and melibiose metabolism. In Escherichia coli, the lacZ gene codes for ,B-galactosidase, the lacY gene codes for lactose permease, and the lacA gene codes for thiogalactoside transacetylase (36). The mel operon of E. coli contains the A and B genes which code for a-galactosidase and melibiose permease, respectively (30). Klebsiella aerogenes possesses both a plasmidborne and a chromosomal lac operon (1, 21, 22, 24). Both K. aerogenes and Salmonella typhimurium possess mel operons similar to the E. coli operon (12,23).The substrate specificities of the lac and mel permeases differ among the various members of the Enterobacteriaceae. The lac permease of E. coli has wide specificity and transports a variety of a-and P-galactosides, including lactose, isopropyl-p-D-thiogalactopyranoside (IPTG), thiomethyl-,3-D-galactopyranoside (TMG), melibiose, and galactose (26). The mel permeases of E. coli and S. typhimurium are similar in specificity and can transport TMG, melibiose, and galactose, but not lactose or IPTG (12,19,26,30). The mel permease of K. aerogenes differs from those of E. coli and S. typhimurium in being able to transport lactose in addition to TMG, melibiose, and galactose (23,35).The rafoperon is plasmidborne in E. coli (18). It codes for the three genes involved in raffinose metabolism: agalactosidase, raffinose permease, and invertase (29,32). All three activities are coordinately induced by melibiose and raffinose (29, 32). Lactose transport by the raffinose permease is competitively inhibited by melibiose and raffinose (32).Erwinia chrysanthemi pv. zeae, the causal agent of soft rot in corn, is a member of the Enterobacteriaceae (34). Only two reports dealing with lactose metabolism in E. chrysanthemi have appeared (6,8) despite the use of lactose fermentation as a taxonomic marker in the classification of the Enterobacteriaceae. The 322 strains of E. chrysanthemi studied by Dickey (3) were all able to hydrolyze o-

show abstract

Section: Downloaded Frommentioning

confidence: 99%

Lactose and melibiose metabolism in Erwinia chrysanthemi

Gray¹,

Lindner²,

Brand³

et al. 1986

J Bacteriol

View full text Add to dashboard Cite

show abstract

“…The relative simplicity of microbial systems, their capacity for rapid evolutionary change, and advances in technology that enable detailed genotypic traceability offer a unique opportunity to log moment-by-moment change in experimental populations, with the potential to contribute to understanding of how genotype shapes phenotype, how phenotype interplays with the environment, and how environment may shape genotype (Mortlock 1982;Lenski et al 1998;Rainey et al 2000;Beaumont et al 2009;Buckling et al 2009;Blount et al 2012;Hindré et al 2012). In the context of adaptive radiation, the bacterium Pseudomonas fluorescens SBW25 has served as a useful model (reviewed within MacLean 2005 andKassen 2009).…”

mentioning

confidence: 99%

Adaptive Divergence in Experimental Populations ofPseudomonas fluorescens. V. Insight into the Niche Specialist Fuzzy Spreader Compels Revision of the ModelPseudomonasRadiation

2013

View full text Add to dashboard Cite

Pseudomonas fluorescens is a model for the study of adaptive radiation. When propagated in a spatially structured environment, the bacterium rapidly diversifies into a range of niche specialist genotypes. Here we present a genetic dissection and phenotypic characterization of the fuzzy spreader (FS) morphotype-a type that arises repeatedly during the course of the P. fluorescens radiation and appears to colonize the bottom of static broth microcosms. The causal mutation is located within gene fuzY (pflu0478)-the fourth gene of the five-gene fuzVWXYZ operon. fuzY encodes a b-glycosyltransferase that is predicted to modify lipopolysaccharide (LPS) O antigens. The effect of the mutation is to cause cell flocculation. Analysis of 92 independent FS genotypes showed each to have arisen as the result of a loss-of-function mutation in fuzY, although different mutations have subtly different phenotypic and fitness effects. Mutations within fuzY were previously shown to suppress the phenotype of mat-forming wrinkly spreader (WS) types. This prompted a reinvestigation of FS niche preference. Time-lapse photography showed that FS colonizes the meniscus of broth microcosms, forming cellular rafts that, being too flimsy to form a mat, collapse to the vial bottom and then repeatably reform only to collapse. This led to a reassessment of the ecology of the P. fluorescens radiation. Finally, we show that ecological interactions between the three dominant emergent types (smooth, WS, and FS), combined with the interdependence of FS and WS on fuzY, can, at least in part, underpin an evolutionary arms race with bacteriophage SBW25F2, to which mutation in fuzY confers resistance.A DAPTIVE radiation-the rapid emergence of phenotypic and ecological diversity within an expanding lineage-is among the most striking of evolutionary phenomena (Darwin 1859;Lack 1947;Dobzhansky 1951;Simpson 1953;Schluter 2000;Kassen 2009;Losos 2010). Fueled by competition and facilitated by ecological opportunity, successive radiations have shaped much of life's diversity. Of central importance are the phenotypic innovations that fashion the fit between organism and environment (Schluter 2000).Understanding the nature of these innovations and the pathways by which they emerge and rise to prominenceoften in parallel across estranged populations experiencing similar environments-is a central issue (Colosimo et al. 2005;Bantinaki et al. 2007;Conte et al. 2012). How mutational processes generate the variation presented to selection (McDonald et al. 2009;Braendle et al. 2010), how genetic architecture underpinning extant phenotypes determines the capacity of lineages to generate new and adaptive phenotypes (Poole et al. 2003;Wagner and Zhang 2011), and how ecological factors drive phenotypic divergence (Schluter 2009) are questions of seminal interest.The relative simplicity of microbial systems, their capacity for rapid evolutionary change, and advances in technology that enable detailed genotypic traceability offer a unique opportunity to log moment-by-...

show abstract

“…We cannot exclude the possibility that there are heretofore unknown metabolic pathways for very specific substrates since numerous hypothetical proteins produced under stress conditions have not been functionally characterized yet. This possibility is exemplified by several cases of the metabolism of rare sugars (13,32). In some cases, a new enzymatic activity can be shown to be derived (44).…”

Section: Discussionmentioning

confidence: 99%

“…Although these MIs are induced by the presence of D-lyxose as the sole carbon source, they exhibit very low levels of activity with this sugar, indicating that they are not primarily responsible for isomerization of D-lyxose to D-xylulose. In addition, Klebsiella pneumoniae PRL-R3 cannot grow on D-lyxose, but mutants of this organism that can grow on D-lyxose have been isolated (32). An enzyme with isomerization activity for D-lyxose and Dmannose was purified from one such mutant, but it seemed to be an MI rather than an LI since it had only weak isomerization activity with D-lyxose.…”

mentioning

confidence: 99%