Researchers at the University of California, Berkeley, identify two regions of the double-pleckstrin homology domain architecture of Rtt106 that mediate histone binding, as they report in the PNAS Early Edition this week. "When histone binding was compromised, Rtt106 localized properly to chromatin but failed to deliver H3K56ac, leading to replication and silencing defects," the Berkeley team found. "Our studies described the structural origins of Rtt106 function, identified a conserved histone-binding surface, and defined a critical role for Rtt106:H3K56ac-binding specificity in silencing and replication-coupled nucleosome turnover," the authors add.
Elsewhere in the Early Edition, a team led by investigators at Utrecht University presents a database-independent proteomics analysis of the ostrich proteome versus the human proteome. Using a mass spectrometry-based approach, and by "implementing several validation steps … we identified approximately 2,500 unique de novo peptide sequences from the ostrich sample with over 900 peptides generating full backbone sequence coverage," it writes. Overall, the Utrecht team says its database-free approach "is generically applicable and has great potential in important proteomics applications such as in the analysis of variable parts of endogenous antibodies or proteins modified by a plethora of complex posttranslational modifications."
In another paper published online in advance in PNAS, Magnus Johansson, Jingji Zhang, and Måns Ehrenberg at Uppsala University describe an assay based on Mg2+ concentration changes "to determine maximal accuracy limits for a complete set of single-mismatch codon–anticodon interactions." The trio says results generated using its method "rationalize the existence of proofreading in code reading and have implications for the understanding of tRNA modifications, as well as of translation error-modulating ribosomal mutations and antibiotics."