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N-Utilization Substance G (NusG) N-terminal domain in the NusG Specialized Paralog (SP), RfaH RfaH is an operon-specific virulence regulator, thought to have arisen from an early duplication of N-Utilization Substance G (NusG). Paralogs of eubacterial NusG, NusG SP (Specialized Paralog of NusG), are more diverse and often found as the first ORF in operons encoding secreted proteins and LPS biosynthesis genes. NusG SP family members are operon-specific transcriptional antitermination factors. NusG is essential in Escherichia coli and is associated with RNA polymerase elongation and Rho-termination in bacteria. In contrast, RfaH is a non-essential protein that controls expression of operons containing an ops (operon polarity suppressor) element in their transcribed DNA. RfaH and NusG are different in their response to Rho-dependent terminators and regulatory targets. The NusG N-terminal (NGN) domain is quite similar in all NusG orthologs, but its C-terminal domains and the linker that separate these two domains are different. The domain organization of NusG and its homologs suggest that the common properties of NusG and RfaH are due to their similar NGN domains. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",