groES

groES is a bacterial gene that encodes the co-chaperonin GroES, also known as Hsp10. Together with GroEL (Hsp60), GroES forms the bacterial GroEL/GroES chaperonin system, which assists in the correct folding of many cytosolic proteins. The groES gene is widely conserved among bacteria and is often studied as part of the operon with groEL.

GroES is a small, around 97-amino-acid subunit that assembles into a homoheptameric ring. This seven-subunit ring acts as a lid that caps one GroEL chamber during the protein-folding cycle. The GroEL complex is a double-ring tetradecamer; GroES binds to the apical surface of one GroEL ring in an ATP-dependent manner, forming a closed, sequestered folding chamber for the substrate protein.

In the typical cycle, an unfolded or misfolded polypeptide binds to the cis GroEL ring in the presence of ATP. ATP binding promoting GroES association leads to the formation of the GroEL-GroES complex, encapsulating the substrate within the folding chamber. Inside this confined environment, the protein can fold away from the cellular milieu. After ATP hydrolysis, GroES dissociates and the folded or partially folded protein is released, with the trans ring proceeding to bind a new substrate in the next cycle.

GroES expression is often upregulated in response to heat stress, and the GroEL/GroES system is essential for viability under stress conditions in many bacteria. The GroES–GroEL system is evolutionarily conserved, with organellar homologs in mitochondria and chloroplasts (often referred to as Hsp10 and Hsp60) performing a related function in those compartments.