Structural characterization of a GNAT family acetyltransferase from Elizabethkingia anophelis bound to acetyl-CoA reveals a new dimeric interface.

General control non-repressible 5 (GCN5)-related N-acetyltransferases (GNATs) catalyse the acetylation of a diverse range of substrates, thereby orchestrating a variety of biological processes within prokaryotes and eukaryotes. GNAT enzymes can catalyze the transfer of an acetyl group from acetyl coenzyme A to substrates such as aminoglycoside antibiotics, amino acids, polyamines, peptides, vitamins, catecholamines, and large macromolecules including proteins. Although GNATs generally exhibit low to moderate sequence identity, they share a conserved catalytic fold and conserved structural motifs. In this current study we characterize the high-resolution X-ray crystallographic structure of a GNAT enzyme bound with acetyl-CoA from Elizabethkingia anophelis, an important multi-drug resistant bacterium. The tertiary structure is comprised of six α-helices and nine ß-strands, and is similar with other GNATs. We identify a new and uncharacterized GNAT dimer interface, which is conserved in at least two other unpublished GNAT structures. This suggests that GNAT enzymes can form at least five different types of dimers, in addition to a range of other oligomers including trimer, tetramer, hexamer, and dodecamer assemblies. The high-resolution structure presented in this study is suitable for future in-silico docking and structure-activity relationship studies.

Evaluation of patients with primary immunodeficiency associated with Bacille Calmette-Guerin (BCG)-vaccine-derived complications.

BACKGROUND: Bacille Calmette-Guerin (BCG) vaccination has a great impact on the prevention of severe complications of tuberculosis. However, in patients with primary immunodeficiencies (PID), it can lead to severe complications such as severe combined immunodeficiency, chronic granulomatous disease, and Mendelian susceptibility to mycobacterial disease. This study highlights the demographics, clinical complications and laboratory parameters among PID patients associated with BCG vaccination side effects. METHODS: One hundred and thirty-seven PID patients with BCGosis were evaluated in this study, based on the complications following BCG vaccination. RESULTS: The mean age of the patients with BCG complications at the time of the first visit was five years. The within-group comparison of patients showed a highly significant incidence of pneumonia and hepatomegaly in severe combined immunodeficiency patients. Furthermore, the immunologic data showed an increase in the overall rates of lymphocytes such as CD3+, CD4+ and CD8 + T cells in Mendelian susceptibility to mycobacterial disease patients. The level of immunoglobulins has also increased in chronic granulomatous disease patients. CONCLUSION: The high rate of undiagnosed PIDs predisposes individuals to a high risk of severe side effects as a result of BCG vaccination, as well as infants that are less than one month of age. Therefore, there is a need for early screening and diagnosis of PIDs before exposing unknown PID status patients to BCG vaccination. The benefits of screening and early diagnosis of PID cannot be overemphasized, especially in patients with a previous family history of immunodeficiency.