Turning on and turning off the arginine deiminase system in oral streptococci

Abstract

The arginine deiminase system in oral streptococci is highly regulated. It requires induction and is repressed by catabolites such as glucose or by aeration. A comparative study of regulation of the system in Streptococcus gordonii ATCC 10558, Streptococcus rattus FA-1, and Streptococcus sanguis NCTC 10904 showed an increase in activity of the system in S. sanguis of some 1467-fold associated with induction-depression of cells previously uninduced-repressed. The activity of the system was assayed in terms of levels of arginine deiminase, the signature enzyme of the system, in permeabilized cells. Increases in enzyme levels associated with induction-depression were less for the other two organisms, mainly because of less severe repression, especially for S. rattus FA-1, which was the least sensitive to catabolite repression or aeration. Regulation of the arginine deiminase system involving induction and catabolite repression was demonstrated also with monoorganism biofilms composed of cells of S. sanguis adherent to glass slides. Fully uninduced-repressed cells from suspension cultures or biofilms were compromised in their abilities to catabolize arginine to protect themselves against acid damage. However, it was found that the system can be rapidly turned on or turned off, although induction-depression did appear to require cell growth. Still, the system could respond rapidly to the availability of arginine to reestablish high capacity for alkali production.

Physiological Characterization of a Heme-Deficient Mutant of Staphylococcus aureus by a Proteomic Approach

“…9B). This system occurs in a variety of bacteria (5) and appears to be induced by arginine under anaerobic conditions and to be regulated by catabolite repression (6), which might explain our observation that the system was not expressed until glucose was depleted (Fig. 3B).…”

Surviving the Acid Test: Responses of Gram-Positive Bacteria to Low pH

“…The level to which this system can be induced may reflect its importance. The degree of induction is 48-fold in S. rattus, 1,467-fold in S. sanguis 10904, and over 300-fold in S. gordonii (61). One should note, however, that pH itself does not seem to be a major factor in ADI expression in oral streptococci.…”

Genetics of Acid Adaptation in Oral Streptococci

“…Thus, protection from acid-mediated damage by the ADS appears to be by a mechanism secondary to other elements expressed in S. sanguis. Nevertheless, the contribution of the ADS to the cells is important, as judged by levels of induction in response to acidification: In S. rattus, AD activity was increased 48-fold; in S. sanguis 10904, 1467-fold; and in S. gordonii, over 300-fold (Curran et al, 1998). These values represent a clear commitment of cellular resources to enzyme production, though they may also reflect the availability of inducer or inducing mechanism(s).…”