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Full-Text Articles in Molecular Biology

Aminoacyl-Trna Synthetase Complexes: Molecular Multitasking Revealed, Corinne D. Hausmann, Michael Ibba Jul 2008

Aminoacyl-Trna Synthetase Complexes: Molecular Multitasking Revealed, Corinne D. Hausmann, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The accurate synthesis of proteins, dictated by the corresponding nucleotide sequence encoded in mRNA, is essential for cell growth and survival. Central to this process are the aminoacyl-tRNA synthetases (aaRSs), which provide amino acid substrates for the growing polypeptide chain in the form of aminoacyl-tRNAs. The aaRSs are essential for coupling the correct amino acid and tRNA molecules, but are also known to associate in higher order complexes with proteins involved in processes beyond translation. Multiprotein complexes containing aaRSs are found in all three domains of life playing roles in splicing, apoptosis, viral assembly, and regulation of transcription and translation. …


Structural And Functional Mapping Of The Archaeal Multi-Aminoacyl-Trna Synthetase Complex, Corinne D. Hausmann, Michael Ibba Jun 2008

Structural And Functional Mapping Of The Archaeal Multi-Aminoacyl-Trna Synthetase Complex, Corinne D. Hausmann, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Methanothermobacter thermautotrophicus contains a multi-aminoacyl-tRNA synthetase complex (MSC) of LysRS, LeuRS and ProRS. Elongation factor (EF) 1A also associates to the MSC, with LeuRS possibly acting as a core protein. Analysis of the MSC revealed that LysRS and ProRS specifically interact with the idiosyncratic N- and C- termini of LeuRS, respectively. EF-1A instead interacts with the inserted CP1 proofreading domain, consistent with models for post-transfer editing by class I synthetases such as LeuRS. Together with previous genetic data, these findings show that LeuRS plays a central role in mediating interactions within the archaeal MSC by acting as a core scaffolding …


Monitoring Lys-TrnaLys Phosphatidylglycerol Transferase Activity, Michael Ibba Jan 2008

Monitoring Lys-TrnaLys Phosphatidylglycerol Transferase Activity, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

In some bacteria Lys-tRNALys is used both in translation and for the specific addition of Lys to phosphatidylglycerol in the cytoplasmic membrane. This reaction is catalyzed by the membrane protein MprF, and the lysyl-phosphatidylglycerol formed contributes to the resistance of these bacteria to various cationic antibacterial molecules. Obtaining proteins and reconstituting an in vitro system mimicking membrane conditions is a major challenge to studying the function of membrane proteins, especially when labile substrates such as Lys-tRNALys are required. Here we report methods to obtain a stable enriched membrane fraction containing MprF, and the techniques necessary to quantitatively monitor …


Distinct Phospho-Forms Of Cortactin Differentially Regulate Actin Polymerization And Focal Adhesions, Anne E. Kruchten, Eugene W. Krueger, Yu Wang, Mark A. Mcniven Jan 2008

Distinct Phospho-Forms Of Cortactin Differentially Regulate Actin Polymerization And Focal Adhesions, Anne E. Kruchten, Eugene W. Krueger, Yu Wang, Mark A. Mcniven

Faculty Publications

Cortactin is an actin-binding protein that is overexpressed in many cancers and is a substrate for both tyrosine and serine/threonine kinases. Tyrosine phosphorylation of cortactin has been observed to increase cell motility and invasion in vivo, although it has been reported to have both positive and negative effects on actin polymerization in vitro. In contrast, serine phosphorylation of cortactin has been shown to stimulate actin assembly in vitro. Currently, the effects of cortactin serine phosphorylation on cell migration are unclear, and furthermore, how the distinct phospho-forms of cortactin may differentially contribute to cell migration has not been directly compared. Therefore, …