May act as a carrier protein for the ROS scavenging lipoyl moiety and/or as a substrate for oxidoreductases such as SpyM50865 and SpyM50866. Lipoylated GcvH-L directly interacts with SpyM50868, which reverses the SirTM-mediated mono-ADP-ribosylation of GcvH-L, and with the oxidoreductase SpyM50865. Is lipoylated on K-56 by LplA2 (SpyM50870) and then mono-ADP-ribosylated on D-27 by SirTM (SpyM50869). The mono-ADP-ribosylation state of GcvH-L might regulate the availability of the lipoyl moiety for redox reactions; ADP-ribosylation would inhibit the interaction of the oxidoreductase with GcvH-L when it is not required, thus ADP-ribosylation of GcvH-L might be acting to keep the response 'off' under non-stress conditions.