Heme is a source of iron for the bacterium Streptococcus pyogenes. It is taken up in part by an ABC transporter (Sia or Hts pathway), which in turn obtains heme from the Shr and Shp proteins. We are studying the factors that control binding of the heme in the SiaA protein; data will be reported on a series of mutants. Detailed studies of the guanidinium-induced denaturation of C58A show that the protein unfolds very slowly, with changes seen for a number of days after the addition of guanidine hydrochloride. The pKa values of the mutants range from 9.0 to 9.4, close to that of WT (9.7). The two NEAT domains of Shr behave similarly in many respects. However, NEAT2 undergoes facile autoreduction as the pH increases.

<i>Streptococcus pyogenes</i> heme uptake pathway

241st National Meeting (2011)

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Streptococcus pyogenes heme uptake pathway