A big congratulation to Benz on his recent paper in JMB that solves an old question about the carboxysome! The alpha-carboxysome, which is formed from at least 10 different proteins, possesses an odd, intrinsically disordered protein named CosS2 that recent work suggests (Cai, F. et al., 2015. Life, 5(2), pp.1141–1171.) is critical for carboxysome assembly. Work on CsoS2 has been hampered by strange behavior of CsoS2 and the fact that its single gene leads to the production of two protein gene products, CsoS2A and CsoS2B. Benz used a combination of molecular biology and biochemistry to identify a programmed ribosomal frameshifting site in the mRNA of csos2. This regulatory element programs the ribosome to make two different polypeptides and therefore create two populations of CsoS2 proteins. It is clear there are functional differences between the two isoforms and, towards future work, Benz is curious about how and why these differences occur.
The reference for the work is:
Chaijarasphong T, Nichols RJ, Kortright KE, Nixon CF, Teng PK, Oltrogge LM, Savage DF. 2016. Programmed Ribosomal Frameshifting Mediates Expression of the α-Carboxysome. J Mol Biol 428: 153–164.