Manisha Upadhyay

Publications (2)7.05 Total impact

• Article: The crystal structures of Lactococcus lactis MG1363 Dps proteins reveal the presence of an N-terminal helix that is required for DNA binding.

  Timothy J Stillman, Manisha Upadhyay, Valia A Norte, Svetlana E Sedelnikova, Maria Carradus, Svetomir Tzokov, Per A Bullough, Claire A Shearman, Michael J Gasson, Colin H Williams, Peter J Artymiuk, Jeffrey Green
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  ABSTRACT: Dps proteins play a major role in the protection of bacterial DNA from damage by reactive oxygen species. Previous studies have implicated the extended lysine-containing N-terminal regions of Dps subunits in DNA binding, but this part of the structure has not previously been observed crystallographically. Here the structures of two Dps proteins (DpsA and DpsB) from Lactococcus lactis MG1363 reveal for the first time the presence of an N-terminal alpha helix that extends from the core of the Dps subunit. Consequently, the N-terminal helices are displayed in parallel pairs on the exterior of the dodecameric Dps assemblies. Both DpsA and DpsB bind DNA. Deletion of the DpsA N-terminal helix impaired DNA binding. The N-terminal Lys residues of Escherichia coli Dps have been implicated in DNA binding. Replacement of the lactococcal DpsA Lys residues 9, 15 and 16 by Glu did not inhibit DNA binding. However, DNA binding was inhibited by EDTA, suggesting a role for cations in DNA binding. In contrast to E. coli, Bacillus brevis and Mycobacterium smegmatis Dps:DNA complexes, in which DNA interacts with crystalline Dps phases, L. lactis DNA:Dps complexes appeared as non-crystalline aggregates of protein and DNA in electron micrographs.
  Molecular Microbiology 09/2005; 57(4):1101-12. · 5.01 Impact Factor
• Article: Zinc uptake, oxidative stress and the FNR‐like proteins of Lactococcus lactis

  Colin Scott, Helen Rawsthorne, Manisha Upadhyay, Claire A. Shearman, Michael J. Gasson, John R. Guest, Jeffrey Green
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  ABSTRACT: Lactococcus lactis ssp. cremoris MG1363 contains two FNR homologues, FlpA and FlpB, encoded by the distal genes of two paralogous operons (orfXA/B-orfYA/B-flpA/B). An flpA flpB double mutant strain is hypersensitive to hydrogen peroxide and has a depleted intracellular Zn(II) pool. The phenotypes of the flp mutant strains suggest that FlpA and FlpB control the expression of high and low affinity ATP-dependent Zn(II) uptake systems, respectively. Plate tests revealed that expression from a orfXB::lac reporter was activated by Cd(II), consistent with other Zn(II)-regulated systems. The link between a failure to acquire Zn(II) and hypersensitivity to oxidative stress suggests that Zn(II) may be required to protect vulnerable protein thiols from oxidation.
  FEMS Microbiology Letters 10/2000; 192(1):85 - 89. · 2.04 Impact Factor