TY - JOUR
T1 - Evolution of Rhodopseudomonas palustris to degrade halogenated aromatic compounds involves changes in pathway regulation and enzyme specificity
AU - Haq, Irshad Ul
AU - Christensen, Annika
AU - Fixen, Kathryn R.
N1 - Publisher Copyright:
© 2024 American Society for Microbiology.
PY - 2024/2
Y1 - 2024/2
N2 - Halogenated aromatic compounds are used in a variety of industrial applications but can be harmful to humans and animals when released into the environment. Microorganisms that degrade halogenated aromatic compounds anaerobically have been isolated but the evolutionary path that they may have taken to acquire this ability is not well understood. A strain of the purple nonsulfur bacterium, Rhodopseudomonas palustris, RCB100, can use 3-chlorobenzoate (3-CBA) as a carbon source whereas a closely related strain, CGA009, cannot. To reconstruct the evolutionary events that enabled RCB100 to degrade 3-CBA, we isolated an evolved strain derived from CGA009 capable of growing on 3-CBA. Comparative whole-genome sequencing of the evolved strain and RCB100 revealed both strains contained large deletions encompassing badM, a transcriptional repressor of genes for anaerobic benzoate degradation. It was previously shown that in strain RCB100, a single nucleotide change in an alicyclic acid coenzyme A ligase gene, named aliA, gives rise to a variant AliA enzyme that has high activity with 3-CBA. When the RCB100 aliA allele and a deletion in badM were introduced into R. palustris CGA009, the resulting strain grew on 3-CBA at a similar rate as RCB100. This work provides an example of pathway evolution in which regulatory constraints were overcome to enable the selection of a variant of a promiscuous enzyme with enhanced substrate specificity.
AB - Halogenated aromatic compounds are used in a variety of industrial applications but can be harmful to humans and animals when released into the environment. Microorganisms that degrade halogenated aromatic compounds anaerobically have been isolated but the evolutionary path that they may have taken to acquire this ability is not well understood. A strain of the purple nonsulfur bacterium, Rhodopseudomonas palustris, RCB100, can use 3-chlorobenzoate (3-CBA) as a carbon source whereas a closely related strain, CGA009, cannot. To reconstruct the evolutionary events that enabled RCB100 to degrade 3-CBA, we isolated an evolved strain derived from CGA009 capable of growing on 3-CBA. Comparative whole-genome sequencing of the evolved strain and RCB100 revealed both strains contained large deletions encompassing badM, a transcriptional repressor of genes for anaerobic benzoate degradation. It was previously shown that in strain RCB100, a single nucleotide change in an alicyclic acid coenzyme A ligase gene, named aliA, gives rise to a variant AliA enzyme that has high activity with 3-CBA. When the RCB100 aliA allele and a deletion in badM were introduced into R. palustris CGA009, the resulting strain grew on 3-CBA at a similar rate as RCB100. This work provides an example of pathway evolution in which regulatory constraints were overcome to enable the selection of a variant of a promiscuous enzyme with enhanced substrate specificity.
KW - 3-chlorobenzoate
KW - 4-fluorobenzoate,anaerobic aromatic compound degradation
KW - Rhodopseudomonas palustris
UR - http://www.scopus.com/inward/record.url?scp=85185703424&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85185703424&partnerID=8YFLogxK
U2 - 10.1128/aem.02104-23
DO - 10.1128/aem.02104-23
M3 - Article
C2 - 38206012
AN - SCOPUS:85185703424
SN - 0099-2240
VL - 90
JO - Applied and environmental microbiology
JF - Applied and environmental microbiology
IS - 2
ER -