Biology subjects

Linares-Pasten, J. A.

Publications and source records attributed to Linares-Pasten, J. A..

5 recordsLinked to original sources

bioRxiv2026

Characterization of a GH17 laminarinase, MlGH17A, from a laminarin polysaccharide utilization locus in the marine bacterium Muricauda lutaonensis

Heterotrophic marine microorganisms have the capability to degrade and metabolize laminarin, which is the most abundant source of energy and nutrients in the marine environment, via enzymes encoded by genes clustered in polysaccharide utilization loci (PULs). In this study, a PUL potentially responsible for laminarin utilization was identified in the genome of the marine bacterium Muricauda lutaonensis strain ISCAR-4703, with conserved synteny in the genus Muricauda. A GH17 laminarinase (MlGH17A) encoded in the newly identified PUL was cloned, produced, and characterized as an endo-acting laminarinase, exhibiting the ability to degrade laminarin and laminari-oligosaccharides with a degree of polymerization (DP) greater than four into laminaribiose, laminaritriose, and laminaritetraose, with laminaritriose as the main product making up >50% of the produced oligosaccharide products. The three-dimensional model of the enzyme revealed the presence of seven putative subsites, including four glycone subsites (-4 to -1) and three aglycone subsites (+1 to +3), with a wide cleft to accommodate branches at the -2 subsite, enabling it to act on {beta}-1,3 linked backbones in polysaccharides with {beta}-1,6 linked branches. This enzyme is, along with the recently characterized {beta}-1,3 glucanosyltransglycosylase (MlGH17B), conserved in several Muricauda species and is suggested to play a crucial role in the utilization of laminarin by these bacteria. ImportanceLaminarin, a {beta}-1,3-glucan with occasional {beta}-1,6 branching, is the most abundant source of energy and nutrients in the marine environment. In this study, polysaccharide utilization loci (PULs) for laminarin degradation were identified in various marine Muricauda species, encoding a range of glycoside hydrolases and transglycosylases. In Muricauda lutaonensis ISCAR-4703, the PUL included two GH17 enzymes, separated by a GH30 enzyme and a major facilitator superfamily (MFS) transporter, a feature observed in all corresponding Muricauda PULs. A novel endoacting laminarinase from the PUL, MlGH17A, was characterized and shown to hydrolyze laminarin into laminaribiose, laminaritriose, and laminaritetraose, with laminaritriose as main product. Bioinformatic analysis showed that the enzyme lacked the typical subdomain found in GH17 plant {beta}-glucanases, leading to a lower number of aglycone subsites (+1 to +3). Instead, MlGH17A possessed more glycone subsites (-1 to -4), attributed to the {beta}3-3 loop, which was longer than in GH17 plant {beta}-glucanases.

biochemistry↗

bioRxiv2023

Acinetobacter guillouiae strain isolated from sludge capable of partially degrade polyethylene terephthalate: genomic and biochemical insights

The escalating accumulation of plastic waste in terrestrial and aquatic ecosystems profoundly threatens environmental health and biodiversity while impacting human well-being. Recently, many microorganisms capable of degrading polyethylene terephthalate (PET) have been reported, primarily sourced from terrestrial soils and marine environments. Notably, the challenge of PET pollution in aquatic environments has remained a persistent research concern. In this study, we present the isolation and characterization of Acinetobacter guillouiae strain I-MWF, obtained from a wastewater treatment plant in Makri, AJK, Pakistan, using molecular phylogenetic analysis based on genome sequencing. Results revealed that this strain exhibits the ability for PET powder degradation, as confirmed by HPLC/LCMS analysis. Furthermore, we conducted whole-genome sequencing using Illumina technology and bioinformatically explored this strains potential repertoire of lipase and esterase enzymes. Under optimized conditions of 23{degrees}C and pH 7 in mineral salt media with PET powder as the sole organic substrate, A. guillouiae I-MWF could degrade partially. Extracellular enzymes yielded PET depolymerization products identified as mono(2- hydroxyethyl) terephthalic acid and terephthalic acid. The sequenced genome of this strain spans 4.61 Mb with a mean G + C content of 38.2%, containing 4,178 coding genes, 71 tRNA, and six rRNA genes. Although no cutinase-like enzymes were identified, our analysis unveiled a diverse array of putative lipases and three esterases, all sharing the typical /{beta} hydrolase fold. Additionally, comprehensive molecular modelling analysis suggested that some of the 18 identified extracellular hydrolases may be involved in polyester enzymatic depolymerization processes.

microbiology↗

bioRxiv2023

Metataxonomic analysis of halophilic archaea community in two geothermal springs sources in southern Tunisian Sahara

In this study, we assess the phylogenetic diversity of the halophilic archaeal community of biotechnological interest that inhabit in geothermal water in southern Tunisia. These waters are usually used for farming purposes, particularly for irrigation of the oases and greenhouses, due to the limited availability of surface freshwater resources and the arid climate. The samples processed from two separated geothermal sources in southern Tunisia based on the Illumina Miseq sequencing approach. Three samples including water, sediment, and halite-soil crust, were collected from downstream of two geothermal springs of Ksar Ghilane (KGH) and Zaouet Al Aness (ZAN) oases. Results showed that several haloarchaea-related members were identified in geothermal springs. The average taxonomic composition showed that 20 genera out of 33 were shared between the two geothermal sources with uneven distribution, where the Halogranum genus is the most represented genus with an abundance of 18.9% and 11.58% for ZAW and KGH, respectively. Several unique site-specific genera were also observed; the case of Halonotius, Halopelagius, Natronorubrum, and Haloarcula in ZAN, and Haloprofundus, Halomarina, Halovivax, Haloplanus, Natrinema, Halobium, Natronoarchaeum, Haloterrigena detected in KGH pool. We noticed that the majority of genus members are usually found in low-salinity ecosystems. The finding of this study suggests that haloarchaea-related members could survive in downstream geothermal sources, which may have resulted from the leaching of salts and minerals through drilling waters creating chemically complex saline systems.

microbiology↗

bioRxiv2019

INTERACTION OF QUERCETIN AND EPIGALLOCATECHIN GALLATE (EGCG) AGGREGATES WITH PANCREATIC LIPASE UNDER SIMPLIFIED INTESTINAL CONDITIONS

Diets rich in flavonoids have been related with low obesity rates, which could be related with their potential to inhibit pancreatic lipase, the main enzyme of fat assimilation. Some flavonoids can aggregate in aqueous medium suggesting that the inhibition mechanism could occur on both molecular and colloidal levels. This study investigates the interaction of two flavonoid aggregates, quercetin and epigallocatechin gallate (EGCG), with pancreatic lipase under simplified intestinal conditions. The stability and the morphology of these flavonoid aggregates were studied in four different solutions: Control (water), salt, low lipase concentration and high lipase concentration. Particles were found by optical microscopy in almost all the solutions tested, except EGCG-control. The results show that the precipitation rate decreases for quercetin and increases for EGCG in salt solution and that lipase stabilize quercetin aggregates. In addition, both flavonoids were shown to precipitate together with pancreatic lipase resulting in a sequestering of the enzyme.

biochemistry↗

bioRxiv2019

INTERACTION BETWEEN MYRICETIN AGGREGATES AND LIPASE UNDER SIMPLIFIED INTESTINAL CONDITIONS

Myricetin, a flavonoid found in the plant kingdom, has previously been identified as a food molecule with beneficial effects against obesity. This property has been related with its potential to inhibit lipase, the enzyme responsible of fat digestion. In this study we investigate the interaction between myricetin and lipase under simplified intestinal conditions from a colloidal point of view. The results show that myricetin form aggregates in aqueous medium and under simplified intestinal condition, where it was found that lipase is in its monomeric form. Although lipase inhibition by myricetin at a molecular level has been reported previously, the results of this study suggest that myricetin aggregates inhibit lipase by a sequestering mechanism as well. The size of these aggregates was determined to be in the range of a few nm to >200 nm.

biochemistry↗