ALT Title: The chaperon CcmS plays a role in carboxysome assembly in cyanobacteria. Cover description: The carboxysome is a specialized organelle-like protein assembly found in cyanobacteria and chemoautotrophs, playing a crucial role in carbon fixation. Understanding how various carboxysome proteins self-assemble into a functional carboxysome structure is vi-tal for both biological research and synthetic engineering applications. Photo from the authors of Cheng et al. shows the dimeric structure of the chaperon protein CcmS and how CcmS facil-itates the assembly of β-carboxysomes in the cyanobacterium Nostoc sp. PCC 7120 by interacting with the shell protein CcmK1 at the shell outer surface. Image credit: Luning Liu.