CspB of an arctic bacterium, Polaribacter irgensii KOPRI 22228, confers extraordinary freeze-tolerance

Abstract

Freezing temperatures are a major challenge for life at the poles. Decreased membrane fluidity, uninvited secondary structure formation in nucleic acids, and protein cold-denaturation all occur at cold temperatures. Organisms adapted to polar regions possess distinct mechanisms that enable them to survive in extremely cold environments. Among the cold-induced proteins, cold shock protein (Csp) family proteins are the most prominent. A gene coding for a Csp-family protein, cspB, was cloned from an arctic bacterium, Polaribacter irgensii KOPRI 22228, and overexpression of cspB greatly increased the freeze-survival rates of Escherichia coli hosts, to a greater level than any previously reported Csp. It also suppressed the cold-sensitivity of an E. coli csp-quadruple deletion strain, BX04. Sequence analysis showed that this protein consists of a unique domain at its N-terminal end and a well conserved cold shock domain at its C-terminal end. The most common mechanism of Csp function in cold adaption is melting of the secondary structures in RNA and DNA molecules, thus facilitating transcription and translation at low temperatures. P. irgensii CspB bound to oligo(dT)-cellulose resins, suggesting single-stranded nucleic acid-binding activity. The unprecedented level of freeze-tolerance conferred by P. irgensii CspB suggests a crucial role for this protein in survival in polar environments.

Eurypsychrophilic acidophiles: From (meta)genomes to low-temperature biotechnologies

“…The response to cold shock also triggers adaptive mechanisms. These include the induction of cold shock proteins and increased expression of chaperones to assist with RNA stability, protein folding, and enzymatic activities, along with increased compatible solute synthesis and/or uptake, extracellular polysaccharide synthesis, or ice interacting proteins (Junge et al, 2006 ; Phadtare and Inouye, 2008 ; Jung et al, 2010 , 2018 ; Galleguillos et al, 2018 ; Kumar et al, 2020 ).…”

Pedobacter fastidiosus sp. nov., isolated from glacial habitats of maritime Antarctica

“…coli transformant, suggesting its role in cold adaptation [37]. The CspB protein of Polaribacter irgensii KOPRI 22228 confers significant freeze tolerance, and thus plays a crucial role in survival under polar conditions [38]. The final protein, CspD, was normally found in mesophilic bacteria.…”

“…The cspA gene of the polar strain Psychromonas arctica KOPRI 22215 was found to increase resistance to freeze-thaw cycles more than 10-fold in the E. coli transformant, suggesting its role in cold adaptation [37]. The CspB protein of Polaribacter irgensii KOPRI 22228 confers significant freeze tolerance, and thus plays a crucial role in survival under polar conditions [38]. The final protein, CspD, was normally found in mesophilic bacteria.…”

Flavobacterium flabelliforme sp. nov. and Flavobacterium geliluteum sp. nov., Two Multidrug-Resistant Psychrotrophic Species Isolated From Antarctica

“…One copy of a conserved cspB gene was found in all analyzed genomes and one copy of cspC gene was present in P7388 T , F. saccharophilum DSM 1811 T and F. pectinovorum DSM 6368 T . The cspB gene isolated from an arctic strain of Polaribacter irgensii (KOPRI 22228), a member of family Flavobacteriaceae, was found to substantially increase tolerance to freezing and thus considered a primary response to ensure freeze-tolerance of its hosts (Jung et al, 2018). Additionally, all strains encode a trigger factor Tgi, which has been suggested as a main cold-related chaperone of an Antarctic strain, Pseudoalteromonas haloplanktis TAC125 (Piette et al, 2010).…”