Endolysins from Antarctic Pseudomonas Display Lysozyme Activity at Low Temperature

Abstract

Organisms specialized to thrive in cold environments (so-called psychrophiles) produce enzymes with the remarkable ability to catalyze chemical reactions at low temperature. Cold activity relies on adaptive changes in the proteins’ sequence and structural organization that result in high conformational flexibility. As a consequence of flexibility, several such enzymes are inherently heat sensitive. Cold-active enzymes are of interest for application in a number of bioprocesses, where cold activity coupled with easy thermal inactivation can be of advantage. We describe the biochemical and functional properties of two glycosyl hydrolases (named LYS177 and LYS188) of family 19 (GH19), identified in the genome of an Antarctic marine Pseudomonas. Molecular evolutionary analysis placed them in a group of characterized GH19 endolysins active on lysozyme substrates, such as peptidoglycan. Enzyme activity peaks at about 25–35 °C and 40% residual activity is retained at 5 °C. LYS177 and LYS188 are thermolabile, with Tm of 52 and 45 °C and half-lives of 48 and 12 h at 37 °C, respectively. Bioinformatics analyses suggest that low heat stability may be associated to temperature-driven increases in local flexibility occurring mainly in a specific region of the polypeptide that is predicted to contain hot spots for aggregation.

Biogenic Synthesis of Copper Nanoparticles Using Bacterial Strains Isolated from an Antarctic Consortium Associated to a Psychrophilic Marine Ciliate: Characterization and Potential Application as Antimicrobial Agents

“…All bacterial strains used in this work were isolated from a consortium associated with the Antarctic ciliate E. focardii and identified as Marinomonas , Rhodococcus, Pseudomonas , Brevundimonas , and Bacillus [ 17 , 18 , 20 ]. All strains were grown at 22 °C on agarized or liquid Luria–Bertani (LB) medium (tryptone 10g/L, yeast extract 5 g/L, and NaCl 5 g/L).…”

“…This microorganism is a free-swimming ciliate, endemic of the oligotrophic coastal sediments of the Terra Nova Bay [ 17 ]. All bacterial strains are identified as Marinomonas (MM) [ 18 ], Rhodococcus (RH), Pseudomonas (PM) [ 19 , 20 , 21 ], Brevundimonas (BM), and Bacillus (BC). All were named with the ”ef1” suffix (ef stands for Euplotes focardii and 1 indicates that is the first strain of the genus isolated from this organism).…”

A myxobacterial GH19 lysozyme with bacteriolytic activity on both Gram-positive and negative phytopathogens

“…The glycoside hydrolase family 19 (GH19) includes chitinases from plants or bacteria, and lysozymes or endolysins from phages. Several bacteriophage-derived endolysins have been biochemically characterized and reported to have antimicrobial activity against Grampositive or Gram-negative bacteria, and are considered to be 'enzybiotics' with good application potential (Orlando et al 2020;Park et al 2014). Among the characterized plant-derived GH19 enzymes, papaya chitinases exhibit bacteriolytic activities against M. lysodeikticus (Huet et al 2006).…”

Identification and Characterization of Three Chitinases with Potential in Direct Conversion of Crystalline Chitin into N,N′-diacetylchitobiose

“…Chitinase Chib0889 belongs to the GH19 family that mainly contains chitinases found in plants [ 46 ]. Two GH19 chitinases, LYS177 and LYS188, from Pseudomonas Ef1 have been reported to have lysozyme activity and they are clustered with phage/prophage endolysins based on the phylogenetic analysis [ 47 ]. However, the GH19 chitinase, Chib0889, of strain DSM 14401 was nested in the cluster of chitinases from Proteobacteria ( Figure S2 ), implying that Chib0889 may function as a chitinase rather than a lysozyme.…”