Enhanced glycosylation of an S‐layer protein enables a psychrophilic methanogenic archaeon to adapt to elevated temperatures in abundant substrates

Abstract

Adaptation to higher temperatures would increase the environmental competitiveness of psychrophiles, organisms that thrive in low‐temperature environments. Methanolobus psychrophilus, a cold wetland methanogen, ‘evolved’ as a mesophile, growing optimally at 30 °C after subculturings, and cells grown with ample substrates exhibited higher integrity. Here, we investigated N‐glycosylation of S‐layer proteins, the major archaeal envelope component, with respect to mesophilic adaptation. Lectin affinity enriched a glycoprotein in cells grown at 30 °C under ample substrate availability, which was identified as the S‐layer protein Mpsy_1486. Four N‐glycosylation sites were identified on Mpsy_1486, which exhibited different glycosylation profiles, with N94 only found in cells cultured at 30 °C. An N‐linked glycosylation inhibitor, tunicamycin, reduced glycosylation levels of Mpsy_1486 and growth at 30 °C, thus establishing a link between S‐layer protein glycosylation and higher temperature adaptation of the psychrophilic archaeon M. psychrophilus.

The Polygonal Cell Shape and Surface Protein Layer of Anaerobic Methane-Oxidizing Methylomirabilislanthanidiphila Bacteria

“…Glycosylation is a frequent post-translational modification in S-layer proteins ( Ristl et al, 2010 ; Sleytr et al, 2014 ), albeit there have been reports of S-layer proteins with limited sugar content ( Peters et al, 1987 ) as well as its absence ( Masuda and Kawata, 1983 ; Li et al, 2018 ). Glycans have been hypothesized to favor protein stability ( Mengele and Sumper, 1992 ; Engelhardt and Peters, 1998 ; Li et al, 2020 ). Interestingly, however, despite the apparent lack of glycosylation, the S-layer of M. lanthanidiphila shows remarkable resilience to disassembly.…”

N‐glycosylation in Archaea—New roles for an ancient posttranslational modification

“…Modification of N‐glycosylation in response to changes in growth medium composition has also been observed in Methanolobus psychrophilus , a psychrophilic (“cold‐loving”) methanogen (Li et al ., 2020). Assessing the N‐glycosylation profile of the S‐layer glycoprotein in this organism revealed that Asn‐879 was modified when the growth medium contained 20 mM trimethylamine or 40 mM ‐ methanol but not when the concentrations of these substrates were reduced to 10 mM and 20 mM, respectively.…”

“…It had been reported previously that growing this organism in trimethylamine at 18°C over a period of years endowed these cells with the ability to grow at 30°C (Chen et al ., 2015). Li and colleagues (Li et al ., 2020) reported that S‐layer glycoprotein Asn‐94 modification was seen in M. psychrophilus cultures grown at 30°C with higher substrate levels but not at 18°C. At the same time, other glycan‐modified S‐layer glycoprotein asparagine residues were not affected by such changes in growth conditions, pointing to the specificity of the temperature‐ and substrate‐related modification of N‐glycosylation patterns reported.…”

Identification of a novel N-linked glycan on the archaellins and S-layer protein of the thermophilic methanogen, Methanothermococcus thermolithotrophicus

“…Mutant studies in various archaea have revealed that interference with the N-glycosylation pathway can negatively impact archaellum assembly and function, pilus clumping, S-layer stability and the subsequent ability of cells to adapt to medium or low osmolarity (8,37). Recently, it was shown that the psychrophilic methanogen, Methanolobus psychrophilus, increases the extent of Nglycosylation on its S-layer proteins in response to growth above optimal temperatures (45).…”