Title: Functional and structural studies of a novel cold-adapted esterase from an Arctic intertidal metagenomic library Fu J, Leiros HK, de Pascale D, Johnson KA, Blencke HM, Landfald B Ref: Applied Microbiology & Biotechnology, 97:3965, 2013 : PubMed
A novel cold-adapted lipolytic enzyme gene, est97, was identified from a high Arctic intertidal zone sediment metagenomic library. The deduced amino acid sequence of Est97 showed low similarity with other lipolytic enzymes, the maximum being 30 % identity with a putative lipase from Vibrio caribbenthicus. Common features of lipolytic enzymes, such as the GXSXG sequence motif, were detected. The gene product was over-expressed in Escherichia coli and purified. The recombinant Est97 (rEst97) hydrolysed various rho-nitrophenyl esters with the best substrate being rho-nitrophenyl hexanoate (K m and k cat of 39 muM and 25.8 s(-1), respectively). This esterase activity of rEst97 was optimal at 35 degrees C and pH 7.5 and the enzyme was unstable at temperatures above 25 degrees C. The apparent melting temperature, as determined by differential scanning calorimetry was 39 degrees C, substantiating Est97 as a cold-adapted esterase. The crystal structure of rEst97 was determined by the single wavelength anomalous dispersion method to 1.6 A resolution. The protein was found to have a typical alpha/beta-hydrolase fold with Ser144-His226-Asp197 as the catalytic triad. A suggested, relatively short lid domain of rEst97 is composed of residues 80-114, which form an alpha-helix and a disordered loop. The cold adaptation features seem primarily related to a high number of methionine and glycine residues and flexible loops in the high-resolution structures.
Title: The microbial diversity of Polar environments is a fertile ground for bioprospecting de Pascale D, De Santi C, Fu J, Landfald B Ref: Mar Genomics, 8:15, 2012 : PubMed
The term bioprospecting has been adopted for systematic searches in nature for new bioactive compounds, genes, proteins, microorganisms and other products with potential for commercial use. Much effort has been focused on microorganisms able to thrive under harsh conditions, including the Polar environments. Both the lipid and protein cellular building blocks of Polar microorganisms are shaped by their adaptation to the permanently low temperatures. In addition, strongly differing environments, such as permafrost, glaciers and sea ice, have contributed to additional functional diversity. Emerging massive-parallel sequencing technologies have revealed the existence of a huge, hitherto unseen diversity of low-abundance phylotypes--the rare biosphere--even in the Polar environments. This realization has further strengthened the need to employ cultivation-independent approaches, including metagenomics and single-cell genomic sequencing, to get comprehensive access to the genetic diversity of microbial communities for bioprospecting purposes. In this review, we present an updated snapshot of recent findings on the molecular basis for adaptation to the cold and the phylogenetic diversities of different Polar environments. Novel approaches in bioprospecting are presented and we conclude by showing recent bioprospecting outcomes in terms of new molecules patented or applied by some biotech companies.
