The second messenger c-di-AMP is essential for aerobic growth in Staphylococcus aureus; however, many aspects of the c-di-AMP signaling network in S. aureus remain to be elucidated. Josh’s research focuses on uncovering the regulatory role of c-di-AMP in glutamine metabolism, a process crucial for bacterial growth. He has identified a novel regulator, PstA, a PII family protein that modulates the transcription of glutamine synthesis genes. These findings reveal a previously unknown aspect of the nitrogen regulatory circuitry in S. aureus.