0
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Crystal structure of the 65-kilodalton amino-terminal fragment of DNA topoisomerase I from the gram-positive model organism Streptococcus mutans

      ,
      Biochemical and Biophysical Research Communications
      Elsevier BV

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Herein we report the first structure of topoisomerase I determined from the gram-positive bacterium, S. mutans . Bacterial topoisomerase I is an ATP-independent type 1A topoisomerase that uses the inherent torsional strain within hyper-negatively supercoiled DNA as an energy source for its critical function of DNA relaxation. Interest in the enzyme has gained momentum as it has proven to be essential in various bacterial organisms. In order to aid in further biochemical characterization, the apo 65-kDa amino-terminal fragment of DNA topoisomerase I from the gram-positive model organism Streptococcus mutans was crystalized and a three-dimensional structure was determined to 2.06 Å resolution via x-ray crystallography. The overall structure illustrates the four classic major domains that create the traditional topoisomerase I “lock” formation comprised of a sizable toroidal aperture atop what is considered to be a highly dynamic body. A catalytic tyrosine residue resides at the interface between two domains and is known to form a 5’ phosphotyrosine DNA-enzyme intermediate during transient single-stranded cleavage required for enzymatic relaxation of hyper negative DNA supercoils. Surrounding the catalytic tyrosine residue is the remainder of the highly conserved active site. Within 5 Å from the catalytic center, only one dissimilar residue is observed between topoisomerase I from S. mutans and the gram-negative model organism E. coli . Immediately adjacent to the conserved active site, however, S. mutans topoisomerase I displays a somewhat unique nine residue loop extension not present in any bacterial topoisomerase I structures previously determined other than that of an extremophile.

          Related collections

          Author and article information

          Journal
          Biochemical and Biophysical Research Communications
          Biochemical and Biophysical Research Communications
          Elsevier BV
          0006291X
          June 2019
          June 2019
          Article
          10.1016/j.bbrc.2019.06.034
          6626674
          31204053
          d3655c82-3113-45b0-a4ef-acc36c093500
          © 2019

          https://www.elsevier.com/tdm/userlicense/1.0/

          http://creativecommons.org/licenses/by/4.0/

          History

          Comments

          Comment on this article