Comparison between ab initio and density functional calculations in the reaction O+(S-4)+H-2((1)Sigma(+)(g))-> OH+((3)Sigma(-))+H(S-2)
JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM
Authors: Moscardo, F; Perez-Jimenez, AJ
Abstract
The reaction between O+ and H-2 has been studied by means of density functional methods. We adopt a combined procedure in which a Hartree-Fock, or GVB-PP calculation, is complemented by the calculation of the correlation energy using a density functional. Four different correlation functionals are used: Perdew's (PF), Becke's (BF), and the more recent ones of Moscardo and San-Fabian (MSF), and Moscardo and Perez-Jimenez (MP). We have also carried out Kohn-Sham calculations combining different exchange-correlation functionals. The functionals MSF and MP, together with the GVB-PP wave function, provide the best numerical results. Bond lengths, dissociation energies, and the more difficult to obtain category the reaction energy,compare favorably with the result of very extensive MRC1-MP2 calculations. (C) 1998 Elsevier Science B.V.
The Replisome-Coupled E3 Ubiquitin Ligase Rtt101(Mms22) Counteracts Mrc1 Function to Tolerate Genotoxic Stress
PLOS GENETICS
Authors: Buser, Raymond; Kellner, Vanessa; Melnik, Andre; Wilson-Zbinden, Caroline; Schellhaas, Rene; Kastner, Lisa; Piwko, Wojciech; Dees, Martina; Picotti, Paola; Maric, Marija; Labib, Karim; Luke, Brian; Peter, Matthias
Abstract
Faithful DNA replication and repair requires the activity of cullin 4-based E3 ubiquitin ligases (CRL4), but the underlying mechanisms remain poorly understood. The budding yeast Cul4 homologue, Rtt101, in complex with the linker Mms1 and the putative substrate adaptor Mms22 promotes progression of replication forks through damaged DNA. Here we characterized the interactome of Mms22 and found that the Rtt101(Mms22) ligase associates with the replisome progression complex during S-phase via the amino-terminal WD40 domain of Ctf4. Moreover, genetic screening for suppressors of the genotoxic sensitivity of rtt101 Delta cells identified a cluster of replication proteins, among them a component of the fork protection complex, Mrc1. In contrast to rtt101 Delta and mms22 Delta cells, mrc1 Delta rtt101 Delta and mrc1 Delta mms22. double mutants complete DNA replication upon replication stress by facilitating the repair/restart of stalled replication forks using a Rad52-dependent mechanism. Our results suggest that the Rtt101(Mms22) E3 ligase does not induce Mrc1 degradation, but specifically counteracts Mrc1's replicative function, possibly by modulating its interaction with the CMG (Cdc45-MCM-GINS) complex at stalled forks.