Molecular insights of inhibition in sickle hemoglobin polymerization upon glutathionylation: hydrogen/deuterium exchange mass spectrometry and molecular dynamics simulation-based approach
In sickle cell anemia, polymerization of hemoglobin in its deoxy state leads to the formation of insoluble fibers that result in sickling of red blood cells. Stereo-specific binding of isopropyl group of βVal6, the mutated amino-acid residue of a tetrameric sickle hemoglobin molecule (HbS), with hydrophobic groove of another HbS tetramer initiates the polymerization. Glutathionylation of βCys93 in HbS was reported to inhibit the polymerization. However, the mechanism of inhibition in polymerization is unknown to date. In our study, the molecular insights of inhibition in polymerization were investigated by monito...
Source: Biochemical Journal - July 5, 2018 Category: Biochemistry Authors: Das, R., Mitra, A., Mitra, G., Maity, D., Bhat, V., Pal, D., Ross, C., Kurpad, A. V., Mandal, A. K. Tags: Research Articles Source Type: research
Anti-{sigma} factor YlaD regulates transcriptional activity of {sigma} factor YlaC and sporulation via manganese-dependent redox-sensing molecular switch in Bacillus subtilis
YlaD, a membrane-anchored anti-sigma () factor of Bacillus subtilis, contains a HX3CXXC motif that functions as a redox-sensing domain and belongs to one of the zinc (Zn)-co-ordinated anti- factor families. Despite previously showing that the YlaC transcription is controlled by YlaD, experimental evidence of how the YlaC–YlaD interaction is affected by active cysteines and/or metal ions is lacking. Here, we showed that the Pyla promoter is autoregulated solely by YlaC. Moreover, reduced YlaD contained Zn and iron, while oxidized YlaD did not. Cysteine substitution in YlaD led to changes in its secondary structure; Cy...
Source: Biochemical Journal - July 5, 2018 Category: Biochemistry Authors: Kwak, M.-K., Ryu, H.-B., Song, S.-H., Lee, J.-W., Kang, S.-O. Tags: Research Articles Source Type: research
Trade-offs with stability modulate innate and mutationally acquired drug resistance in bacterial dihydrofolate reductase enzymes
Structural stability is a major constraint on the evolution of protein sequences. However, under strong directional selection, mutations that confer novel phenotypes but compromise structural stability of proteins may be permissible. During the evolution of antibiotic resistance, mutations that confer drug resistance often have pleiotropic effects on the structure and function of antibiotic-target proteins, usually essential metabolic enzymes. In the present study, we show that trimethoprim (TMP)-resistant alleles of dihydrofolate reductase from Escherichia coli (EcDHFR) harboring the Trp30Gly, Trp30Arg or Trp30Cys mutatio...
Source: Biochemical Journal - June 29, 2018 Category: Biochemistry Authors: Matange, N., Bodkhe, S., Patel, M., Shah, P. Tags: Research Articles Source Type: research
DIS3 isoforms vary in their endoribonuclease activity and are differentially expressed within haematological cancers
DIS3 (defective in sister chromatid joining) is the catalytic subunit of the exosome, a protein complex involved in the 3'–5' degradation of RNAs. DIS3 is a highly conserved exoribonuclease, also known as Rrp44. Global sequencing studies have identified DIS3 as being mutated in a range of cancers, with a considerable incidence in multiple myeloma. In this work, we have identified two protein-coding isoforms of DIS3. Both isoforms are functionally relevant and result from alternative splicing. They differ from each other in the size of their N-terminal PIN (PilT N-terminal) domain, which has been shown to have endorib...
Source: Biochemical Journal - June 29, 2018 Category: Biochemistry Authors: Robinson, S. R., Viegas, S. C., Matos, R. G., Domingues, S., Bedir, M., Stewart, H. J. S., Chevassut, T. J., Oliver, A. W., Arraiano, C. M., Newbury, S. F. Tags: Research Articles Source Type: research
SINHCAF/FAM60A and SIN3A specifically repress HIF-2{alpha} expression
The SIN3A–HDAC (histone deacetylase) complex is a master transcriptional repressor, required for development but often deregulated in disease. Here, we report that the recently identified new component of this complex, SINHCAF (SIN3A and HDAC-associated factor)/FAM60A (family of homology 60A), links the SIN3A–HDAC co-repressor complex function to the hypoxia response. We show that SINHCAF specifically represses HIF-2α mRNA and protein expression, via its interaction with the transcription factor SP1 (specificity protein 1) and recruitment of HDAC1 to the HIF-2α promoter. SINHCAF control over HIF-2&a...
Source: Biochemical Journal - June 29, 2018 Category: Biochemistry Authors: Biddlestone, J., Batie, M., Bandarra, D., Munoz, I., Rocha, S. Tags: Research Articles Source Type: research
