Eis, a novel family of arylalkylamine N-acetyltransferase (EC 2.3.1.87)

Bang-Ce Ye,Qian Pan,Feng-Lan Zhao

doi:10.1038/s41598-018-20802-6

Abstract

Enhanced intracellular survival (Eis) proteins were found to enhance the intracellular survival of mycobacteria in macrophages by acetylating aminoglycoside antibiotics to confer resistance to these antibiotics and by acetylating DUSP16/MPK-7 to suppress host innate immune defenses. Eis homologs composing of two GCN5 N-acetyltransferase regions and a sterol carrier protein fold are found widely in gram-positive bacteria. In this study, we found that Eis proteins have an unprecedented ability to acetylate many arylalkylamines, are a novel type of arylalkylamine N-acetyltransferase AANAT (EC 2.3.1.87). Sequence alignment and phyletic distribution analysis confirmed Eis belongs to a new aaNAT-like cluster. Among the cluster, we studied three typical Eis proteins: Eis_Mtb from Mycobacterium tuberculosis, Eis_Msm from Mycobacterium smegmatis, and Eis_Sen from Saccharopolyspora erythraea. Eis_Mtb prefers to acetylate histamine and octopamine, while Eis_Msm uses tyramine and octopamine as substrates. Unlike them, Eis_Sen exihibits good catalytic efficiencies for most tested arylalkylamines. Considering arylalkylamines such as histamine plays a fundamental role in immune reactions, future work linking of AANAT activity of Eis proteins to their physiological function will broaden our understanding of gram-positive pathogen-host interactions. These findings shed insights into the molecular mechanism of Eis, and reveal potential clinical implications for many gram-positive pathogens.

Highlights

The emergence of multidrug-resistant and extensively drug-resistant (XDR) Mycobacterium tuberculosis is a serious global threat
Enhanced intracellular survival (Eis) proteins are widely found in other gram-positive bacteria, in addition to mycobacteria, and they have a complex, tripartite-fold structure that is formed by two Gcn5-related N-acetyltransferase (GNAT) domains (IPR000182; about 140–150 amino acids) and a C-terminal animal sterol carrier protein region (SCP2 domain)
Among 2369 Actinomycetales Eis proteins, 1868 proteins are found in Mycobacteria

Summary

Results and Discussion

Eis enzymes are found mostly in Gram-positive bacteria. Eis proteins contain N-terminal GNAT, central GNAT, and C-terminal SCP2 domains. The consequences of superimposition analysis illustrated that N-acyltransferase superfamily structure in Eis enzymes is very similar to the structure of aaNAT2 especially Eis_Msm is the most similar because of their the lowest r.m.s. deviation value, which further indicated that Eis enzymes are capable of acetylating arylalkylamines as well as aaNATs. Our study revealed that Eis enzyme was a novel family of arylalkylamine N-acetyltransferase (aaNAT, EC 2.3.1.87) catalyzing the generation of N-acylarylalkylamides from the short chain acyl-CoA and a broad array of corresponding arylalkylamine substrates, the catalytic efficiency was lower than that of the typical aaNATs. As well as aaNAT2, Eis was less discriminatory for the amine substrates including dopamine, histamine, tyramine, octopamine, phenethylamine, tryptamine, and serotonin.

Protein Source

Materials and Methods

Additional Information