Rabbit Anti-Human SSB (internal) Polyclonal antibody

The conserved ribosome-associated complex (RAC) consisting of Zuo1 (Hsp40) and Ssz1 (non-canonical Hsp70) acts together with the ribosome-bound Hsp70 chaperone Ssb in de novo protein folding at the ribosomal tunnel exit. Current models suggest that the function of Ssz1 is confined to the support of Zuo1, however, it is not known whether RAC by itself serves as a chaperone for nascent chains. Here we show that, via its rudimentary substrate binding domain (SBD), Ssz1 directly binds to emerging nascent chains prior to Ssb. Structural and biochemical analyses identify a conserved LP-motif at the Zuo1 N-terminus forming a polyproline-II helix, which binds to the Ssz1-SBD as a pseudo-substrate. The LP-motif competes with nascent chain binding to the Ssz1-SBD and modulates nascent chain transfer. The combined data indicate that Ssz1 is an active chaperone optimized for transient, low-affinity substrate binding, which ensures the flux of nascent chains through RAC/Ssb. The ribosome-associated complex (RAC), which contains the Hsp40 protein Zuo1 and the non-canonical Hsp70 protein Ssz1 forms a chaperone triad with the fungal-specific Hsp70 protein Ssb. Here the authors combine X-ray crystallography, crosslinking and biochemical experiments and present the structure of the Zuo1 N-terminus bound to Ssz1 and demonstrate that Ssz1 is an active chaperone for nascent chains.

Geant4-DNA was used to calculate the direct DNA breaks due to the alpha and proton particles. For alpha particles with the energy of smaller than 1 MeV, the number of Single-Strand Breaks (SSBs), Double-Strand Breaks (DSBs) and the dose were found to increase. Beyond 1 MeV energy, SSB, DSB and Dose had a falling trend. In the case of DSBs, however, the alpha yields increased from 3.67 (GyGbp)(-1) with the energy of 0.1 MeV to 6.43 (GyGbp)(-1) at 1 MeV. Beyond 1 MeV energy, the yields decreased to 1.37 (GyGbp)(-1) at 30 MeV. The ratio of alpha DSB yields to proton DSB yields increased from 0.1 MeV to 0.5 MeV, but, after 0.5 MeV, the trend changed to a decrease. The calculated results, demonstrated that the difference between alpha and proton SSB yields is not significant, while it is considerable for DSB yields especially with the energy of 2 MeV.