| Abstract |
In their recent manuscript, Protective roles of highly conserved motif 1 in tardigrade cytosolic-abundant heat soluble protein in extreme environments, Kang et al. (2024) investigate the putative role of motif 1 of a cytoplasmic-abundant heat-soluble (CAHS) protein, PrCAHS 1, in desiccation protection. To do so, Kang et al. (2024) test the ability of different regions of PrCAHS 1 to confer protection to the desiccation-sensitive enzyme lactate dehydrogenase (LDH). In doing this, they compare how mixtures with different mass ratios of LDH and regions of PrCAHS 1 retain LDH activity after drying and rehydration. However, another way of comparing the protective capacity of protectants with different molecular weights is to compare their protective capacity at similar molar ratios. Since the 19-mer motif 1 of PrCAHS 1 has a molecular weight that is approximately 11 times lower than full-length PrCAHS 1, choices about how comparisons (weight vs. molar comparisons) are made could influence the outcome of the comparison. This led us to reanalyze the LDH protection data for PrCAHS 1 and motif 1 of PrCAHS 1 converting reported mass ratios to molar ratios, and performing a statistical analysis to compare LDH activity across different molar ratios (Figure 1a,b). This reanalysis confirmed the finding reported by Kang et al. that at similar molar ratios, motif 1 of PrCAHS 1 outperforms the full-length PrCAHS 1 protein in protecting LDH during drying. However, this result was surprising to us, since other full-length proteins from the CAHS family are reported to provide robust protection to LDH during drying (Biswas et al., 2024; Boothby et al., 2017; Hesgrove et al., 2021; Kc et al., 2024; Nguyen et al., 2022; Packebush et al., 2023; Piszkiewicz et al., 2019; Sanchez-Martinez et al., 2024) and do so more efficiently than their individual domains (Biswas et al., 2024; Hesgrove et al., 2021; Packebush et al., 2023). This observation raises the question of whether the protective role of CAHS motif 1 is a conserved feature among other CAHS proteins. |
, Thomas C. Boothby 
