Poster abstracts
Poster number 50 submitted by Annie Urban
The Effects of S21 Paralogs on Translation in Agrobacterium fabrum
Annie Urban (OSU Department of Microbiology, OSU Center for RNA Biology), Fawwaz Naeem (OSU Center for RNA Biology, Ohio State Biochemistry Program), Yaowen Deng (OSU Center for RNA Biology, OSU Biophysics Program), Ralf Bundschuh, Kurt Fredrick (OSU Department of Microbiology, OSU Center for RNA Biology, Ohio State Biochemistry Program)
Abstract:
Ribosomal protein bS21 forms part of the mRNA binding channel of the small (30S) subunit of the bacterial ribosome. Located near the anti-Shine-Dalgarno (ASD) sequence of 16S rRNA, bS21 can influence mRNA-rRNA base pairing during initiation in Escherichia coli. Phylogenetically, bS21 is one of the most variable proteins of the bacterial ribosome. Multiple lineages have lost bS21, while other species encode multiple versions of the protein (1). Recently, it was shown that production of bS21 is autoregulated in Flavobacterium johnsoniae by ribosomes lacking bS21 (2). Interestingly, bS21 is the most common phage-encoded ribosomal protein, and it has been suggested that incorporation of phage bS21 into host ribosomes can perturb protein synthesis during late-stage infection (3,4).
In Agrobacterium fabrum, there are three different rpsU (bS21) genes, denoted rpsU-A, rpsU-B, and rpsU-C. Analysis of RNA-seq data from various prior studies suggests that these three genes are differentially regulated. In this work, we have made precise allelic replacements to elucidate the roles of these rpsU genes. Deletion of rpsU-A causes a very severe growth defect, indicating the functional importance of this gene, whereas the deletion of rpsU-B and/or rpsU-C confers modest defects. In the context of rpsU-B rpsU-C, the coding region of rpsU-A was replaced with that of rpsU-B, rpsU-C, or each of three phage-encoded rpsU genes. Each of the resulting isogenic strains contains a homogeneous population of ribosomes with one version of bS21. The strains exhibit variable growth rates, with larger defects seen for strains harboring phage bS21. Ribosome profiling of these strains suggests that bS21A-containing ribosomes and bS21C-containing ribosomes are functionally identical, while bS21B-containing ribosomes fail to translate a small subset of genes on the pAT plasmid. Current work is focused on the molecular basis of this translational regulation.
References:
(1) Yutin N, Puigbò P, Koonin EV, Wolf YI. Phylogenomics of prokaryotic ribosomal proteins. PLoS One. 2012;7(5)
(2) McNutt ZA, Roy B, Gemler BT, Shatoff EA, Moon K-M, Foster LJ, Bundschuh R, Fredrick K. 2023. Ribosomes lacking bS21 gain function to regulate protein synthesis in Flavobacterium johnsoniae. Nucleic Acids Research 51:1927–1942.
(3) Chen L-X, Jaffe AL, Borges AL, Penev PI, Nelson TC, Warren LA, Banfield JF. 2022. Phage-encoded ribosomal protein S21 expression is linked to late-stage phage replication. ISME Communications 2:31.
(4) Mizuno CM, Guyomar C, Roux S, Lavigne R, Rodriguez-Valera F, Sullivan MB, Gillet R, Forterre P, Krupovic M. 2019. Numerous cultivated and uncultivated viruses encode ribosomal proteins. Nat Commun 10:752.
Keywords: Ribosome heterogeneity, Agrobacterium , Phage