Chaperonin Abundance Enhances Bacterial Fitness.

Anirban Dutta,C. M. Santosh Kumar,Kritika Chugh,Sharmila S. Mande,Vishnuvardhan Mahamkali,Peter A. Lund,Shekhar C. Mande,Tungadri Bose

doi:10.3389/fmolb.2021.669996

Abstract

The ability of chaperonins to buffer mutations that affect protein folding pathways suggests that their abundance should be evolutionarily advantageous. Here, we investigate the effect of chaperonin overproduction on cellular fitness in Escherichia coli. We demonstrate that chaperonin abundance confers 1) an ability to tolerate higher temperatures, 2) improved cellular fitness, and 3) enhanced folding of metabolic enzymes, which is expected to lead to enhanced energy harvesting potential.

Highlights

Chaperonins are found in nearly every organism across all domains of life, and are essential in all cases tested to date, in some cases non-essential paralogues are found (Lund, 2009; Kumar, 2017)
Proteomic studies (Table 1) followed by flux balance analysis (FBA) (Tables 2, 3) suggest that the acquired fitness advantage could be attributed to an enriched set of metabolic enzymes
Chaperonin depletion was observed to induce the enrichment of the compensatory chaperone, trigger factor (TF) (Supplementary Figure 1A; Table 1), which may act as a holdase for the GroE client proteins (Hartl and Hayer-Hartl, 2002)

Summary

Introduction

Chaperonins are found in nearly every organism across all domains of life, and are essential in all cases tested to date, in some cases non-essential paralogues are found (Lund, 2009; Kumar, 2017). The GroE chaperonin system of E. coli, consisting of the 60 kDa GroEL and the 10 kDa GroES proteins assembled into ring complexes of 14 and seven sub-units, respectively, is encoded by the groE operon (Tilly and Georgopoulos, 1982; Bukau and Horwich, 1998; Balchin et al, 2016) This operon is expressed principally from two promoters, one utilized in the presence of housekeeping sigma factor σ70, and the other, which is strongly induced due to the accumulation of unfolded proteins, in the presence of the alternative sigma factor, σ32 (RpoH) (Kusukawa and Yura, 1988; Lund, 2001; Kumar et al, 2015; Schumann, 2017). Combined loss of TF and DnaK is deleterious to cells, groEL and groES are the only chaperone encoding genes in E. coli that are essential under all conditions (Fayet et al, 1989)

Methods

Results

Conclusion