Structural and functional analysis of a novel psychrophilic β-mannanase from Glaciozyma antarctica PI12

Abstract

The structure of a novel psychrophilic β-mannanase enzyme from Glaciozyma antarctica PI12 yeast has been modelled and analysed in detail. To our knowledge, this is the first attempt to model a psychrophilic β-mannanase from yeast. To this end, a 3D structure of the enzyme was first predicted using a threading method because of the low sequence identity (<30%) using MODELLER9v12 and simulated using GROMACS at varying low temperatures for structure refinement. Comparisons with mesophilic and thermophilic mannanases revealed that the psychrophilic mannanase contains longer loops and shorter helices, increases in the number of aromatic and hydrophobic residues, reductions in the number of hydrogen bonds and salt bridges and numerous amino acid substitutions on the surface that increased the flexibility and its efficiency for catalytic reactions at low temperatures.

Novel yeast taxa from the cold: description of Cryolevonia giraudoae sp. nov. and Camptobasidium gelus sp. nov.

“…Ice samples were obtained from two locations in Patagonia and one in Antarctica: (i) Castaño Overa glacier at Mount Tronador (71°50′W, 41°11′S) in summer of 2014; and (ii) Perito Moreno glacier (73°51′W, 49°15′S) in the summer of 2008 [11]; and Bellingshausen sea (61°00′W, 60°51′S) in the summer of 2012. The surface of the ice samples was melted and discarded, and the remaining ice was superficially rinsed with sterile distilled water and melted in aseptic conditions.…”

“…Also, it will be important to expand the studies of the mechanisms that enable survival in cold temperatures, including the production of novel molecules with biotechnological applications, such as cold active enzymes and antifreeze proteins [9][10][11]27]. The genetic diversity present in permanently cold habitats like glacial ice or permafrost needs to be urgently preserved, since most of these are endangered as a result of global warming [28,29].…”

“…The genus Camptobasidium comprises a single species, Camptobasidium hydrophilum, a slow-growing psychrophilic fungus without a yeast stage [2], whereas Glaciozyma contains four psychrophilic yeast species: G. antarctica, G. martinii, G. watsonii and G. litoralis [4,8]. In recent years, these four species, together with other psychrophilic yeasts are being extensively studied as a source of cold active proteins and enzymes of high biotechnological value [9][10][11]. Also, the strategies evolved by these taxa to cope with cold conditions are a matter of substantial investigation nowadays [8].…”

β-Mannanase Activity of Yeasts Isolated in Antarctic

“…Характерной чертой таких энзимов является сочетание высокой активности при низких температурах с низкой термостабильностью, что связано с более высокой подвижностью молекулы по сравнению с протеинами мезо-и термофильных микроорганизмов, однако описаны и исключения из этого правила [4,5].…”

“…Растущий интерес к этому энзиму связан с его огромным потенциалом в области биоконверсии агропромышленных остатков, а также в пищевой, кормовой и деревообрабатывающей отраслях, газо-и нефтедобыче, производстве детергентов и биотоплива [6,7]. На сегодняшний день имеется ряд работ, посвященных изучению дрожжевых продуцентов энзимов маннан-деградирующего комплекса, демонстрирующих широкие возможности использования этой группы микроорганизмов для получения промышленно важных энзимов [5,8,9].…”