HSP90 buffers newly induced mutations in massively mutated plant lines

Abstract

(300 words)Robustness to both genetic and environmental change is an emergent feature of living systems.Loss of phenotypic robustness can be associated with increased penetrance of genetic variation.In model organisms and in humans, the phenotypic consequences of standing genetic variation can be buffered by the molecular chaperone HSP90. However, it has been argued that HSP90 has the opposite effect on newly introduced genetic variation. To test the buffering effect of HSP90 on new mutations, we introduced vast numbers of mutations into wild-type and HSP90-reduced plants and assessed embryonic lethality and early seedling phenotypes for thousands of offspring. Although the levels of newly introduced mutations were similar in the two backgrounds, the HSP90-reduced plants showed a significantly greater frequency of embryonic

Heat shock protein gene expression is higher and more variable with thermal stress and mutation accumulation inDaphnia

“…Because missense mutations can promote protein misfolding and HSPs aid in correct folding, HSP90 has gained a reputation as a "capacitor for mutation" by providing an additional barrier between genotype and phenotype . The idea is that buffering against protein misfolding stores variation that can then be 'released' if the cellular pool of HSP90 becomes depleted , as has been demonstrated by mutant lines, knockouts/knockdowns of HSP90, pharmacological interference, and among natural populations that vary in their HSP90 expression (Rohner et al, 2013, Hummel et al, 2017, Mason et al, 2018. A mutation accumulation experiment with hypermutator strains of yeast revealed an enrichment of HSP90 expression (Zabinsky et al, 2019a), underscoring the need for a deeper understanding of the impact of mutation and of intraspecific variation in patterns of HSP expression.…”