Pereira GV

References (2)

Title : Degradation of complex arabinoxylans by human colonic Bacteroidetes - Pereira_2021_Nat.Commun_12_459
Author(s) : Pereira GV , Abdel-Hamid AM , Dutta S , D'Alessandro-Gabazza CN , Wefers D , Farris JA , Bajaj S , Wawrzak Z , Atomi H , Mackie RI , Gabazza EC , Shukla D , Koropatkin NM , Cann I
Ref : Nat Commun , 12 :459 , 2021
Abstract : Some Bacteroidetes and other human colonic bacteria can degrade arabinoxylans, common polysaccharides found in dietary fiber. Previous work has identified gene clusters (polysaccharide-utilization loci, PULs) for degradation of simple arabinoxylans. However, the degradation of complex arabinoxylans (containing side chains such as ferulic acid, a phenolic compound) is poorly understood. Here, we identify a PUL that encodes multiple esterases for degradation of complex arabinoxylans in Bacteroides species. The PUL is specifically upregulated in the presence of complex arabinoxylans. We characterize some of the esterases biochemically and structurally, and show that they release ferulic acid from complex arabinoxylans. Growth of four different colonic Bacteroidetes members, including Bacteroides intestinalis, on complex arabinoxylans results in accumulation of ferulic acid, a compound known to have antioxidative and immunomodulatory properties.
ESTHER : Pereira_2021_Nat.Commun_12_459
PubMedSearch : Pereira_2021_Nat.Commun_12_459
PubMedID: 33469030
Gene_locus related to this paper: 9bace-k9e1w0 , 9bace-b3c976 , 9bace-e2ncy6 , 9bace-e2ncy7 , 9bace-a0a380yku1 , 9bace-b3c969 , 9bace-b3c974 , 9bace-b3c975

Title : Enzymatic Mechanism for Arabinan Degradation and Transport in the Thermophilic Bacterium Caldanaerobius polysaccharolyticus - Wefers_2017_Appl.Environ.Microbiol_83_
Author(s) : Wefers D , Dong J , Abdel-Hamid AM , Paul HM , Pereira GV , Han Y , Dodd D , Baskaran R , Mayer B , Mackie RI , Cann I
Ref : Applied Environmental Microbiology , 83 : , 2017
Abstract : The plant cell wall polysaccharide arabinan provides an important supply of arabinose, and unraveling arabinan-degrading strategies by microbes is important for understanding its use as a source of energy. Here, we explored the arabinan-degrading enzymes in the thermophilic bacterium Caldanaerobius polysaccharolyticus and identified a gene cluster encoding two glycoside hydrolase (GH) family 51 alpha-l-arabinofuranosidases (CpAbf51A, CpAbf51B), a GH43 endoarabinanase (CpAbn43A), a GH27 beta-l-arabinopyranosidase (CpAbp27A), and two GH127 beta-l-arabinofuranosidases (CpAbf127A, CpAbf127B). The genes were expressed as recombinant proteins, and the functions of the purified proteins were determined with para-nitrophenyl (pNP)-linked sugars and naturally occurring pectin structural elements as the substrates. The results demonstrated that CpAbn43A is an endoarabinanase while CpAbf51A and CpAbf51B are alpha-l-arabinofuranosidases that exhibit diverse substrate specificities, cleaving alpha-1,2, alpha-1,3, and alpha-1,5 linkages of purified arabinan-oligosaccharides. Furthermore, both CpAbf127A and CpAbf127B cleaved beta-arabinofuranose residues in complex arabinan side chains, thus providing evidence of the function of this family of enzymes on such polysaccharides. The optimal temperatures of the enzymes ranged between 60 degrees C and 75 degrees C, and CpAbf43A and CpAbf51A worked synergistically to release arabinose from branched and debranched arabinan. Furthermore, the hydrolytic activity on branched arabinan oligosaccharides and degradation of pectic substrates by the endoarabinanase and l-arabinofuranosidases suggested a microbe equipped with diverse activities to degrade complex arabinan in the environment. Based on our functional analyses of the genes in the arabinan degradation cluster and the substrate-binding studies on a component of the cognate transporter system, we propose a model for arabinan degradation and transport by C. polysaccharolyticusIMPORTANCE Genomic DNA sequencing and bioinformatic analysis allowed the identification of a gene cluster encoding several proteins predicted to function in arabinan degradation and transport in C. polysaccharolyticus The analysis of the recombinant proteins yielded detailed insights into the putative arabinan metabolism of this thermophilic bacterium. The use of various branched arabinan oligosaccharides provided a detailed understanding of the substrate specificities of the enzymes and allowed assignment of two new GH127 polypeptides as beta-l-arabinofuranosidases able to degrade pectic substrates, thus expanding our knowledge of this rare group of glycoside hydrolases. In addition, the enzymes showed synergistic effects for the degradation of arabinans at elevated temperatures. The enzymes characterized from the gene cluster are, therefore, of utility for arabinose production in both the biofuel and food industries.
ESTHER : Wefers_2017_Appl.Environ.Microbiol_83_
PubMedSearch : Wefers_2017_Appl.Environ.Microbiol_83_
PubMedID: 28710263