7U1C

Structure of EstG crystalized with SO4 and Tris

Summary for 7U1C

• Entry DOI: 10.2210/pdb7u1c/pdb
• Descriptor: Beta-lactamase domain-containing protein, SULFATE ION, SODIUM ION, ... (5 entities in total)
• Functional Keywords: ccna_01638, alpha/beta fold, hydrolase, estg, beta-lactamase binding protein
• Biological source: Caulobacter vibrioides
• Total number of polymer chains: 1
• Total formula weight: 50163.54

Authors

Gabelli, S.B.,Chen, Z. (deposition date: 2022-02-20, release date: 2023-01-11, Last modification date: 2023-10-25)

Primary citation

Daitch, A.K.,Orsburn, B.C.,Chen, Z.,Alvarez, L.,Eberhard, C.D.,Sundararajan, K.,Zeinert, R.,Kreitler, D.F.,Jakoncic, J.,Chien, P.,Cava, F.,Gabelli, S.B.,Goley, E.D.
EstG is a novel esterase required for cell envelope integrity in Caulobacter.
Curr.Biol., 33:228-240.e7, 2023

PubMed Abstract: Proper regulation of the bacterial cell envelope is critical for cell survival. Identification and characterization of enzymes that maintain cell envelope homeostasis is crucial, as they can be targets for effective antibiotics. In this study, we have identified a novel enzyme, called EstG, whose activity protects cells from a variety of lethal assaults in the ⍺-proteobacterium Caulobacter crescentus. Despite homology to transpeptidase family cell wall enzymes and an ability to protect against cell-wall-targeting antibiotics, EstG does not demonstrate biochemical activity toward cell wall substrates. Instead, EstG is genetically connected to the periplasmic enzymes OpgH and BglX, responsible for synthesis and hydrolysis of osmoregulated periplasmic glucans (OPGs), respectively. The crystal structure of EstG revealed similarities to esterases and transesterases, and we demonstrated esterase activity of EstG in vitro. Using biochemical fractionation, we identified a cyclic hexamer of glucose as a likely substrate of EstG. This molecule is the first OPG described in Caulobacter and establishes a novel class of OPGs, the regulation and modification of which are important for stress survival and adaptation to fluctuating environments. Our data indicate that EstG, BglX, and OpgH comprise a previously unknown OPG pathway in Caulobacter. Ultimately, we propose that EstG is a novel enzyme that instead of acting on the cell wall, acts on cyclic OPGs to provide resistance to a variety of cellular stresses.

PubMed: 36516849
DOI: 10.1016/j.cub.2022.11.037

Experimental method

X-RAY DIFFRACTION (2.09 Å)