Insights into catalysis by a knotted TrmD tRNA methyltransferase

The crystal structure of Escherichia coli tRNA (guanosine-1) methyltransferase (TrmD) complexed with S-adenosyl homocysteine (AdoHcy) has been determined at 2.5A resolution. TrmD, which methylates G37 of tRNAs containing the sequence G36pG37, is a homo-dimer. Each monomer consists of a C-terminal domain connected by a flexible linker to an N-terminal AdoMet-binding domain. The two bound AdoHcy moieties are buried at the bottom of deep clefts. The dimer structure appears integral to the formation of the catalytic center of the enzyme and this arrangement strongly suggests that the anticodon loop of tRNA fits into one of these clefts for methyl transfer to occur. In addition, adjacent hydrophobic sites in the cleft delineate a defined pocket, which may accommodate the GpG sequence during catalysis. The dimer contains two deep trefoil peptide knots and a peptide loop extending from each knot embraces the AdoHcy adenine ring. Mutational analyses demonstrate that the knot is important for AdoMet binding and catalytic activity, and that the C-terminal domain is not only required for tRNA binding but plays a functional role in catalytic activity.status: publishe

Multicenter Study of Human Papillomavirus and the Human Papillomavirus Vaccine: Knowledge and Attitudes among People of African Descent

Objective. To compare knowledge and attitudes of human papillomavirus (HPV) and the vaccine between different cultures of African descent. Methods. A cross-sectional survey of 555 African-Americans and Afro-Caribbeans residing in the US and the Bahamas (BHM) was conducted. Results. General knowledge about HPV and the HPV vaccine differed between the two countries significantly. Bahamian respondents were less likely to have higher numbers of correct knowledge answers when compared to Americans (Adjusted Odds Ratio [Adj. OR] 0.47, 95% Confidence Interval [CI] 0.30–0.75). Older age, regardless of location, was also associated with answering fewer questions correctly (Adj. OR 0.61, 95% CI 0.40–0.92). Attitudes related to HPV vaccination were similar between the US and BHM, but nearly 80% of BHM respondents felt that children should not be able to receive the vaccine without parental consent compared to 57% of American respondents. Conclusions. Grave lack of knowledge, safety and cost concerns, and influence of parental restrictions may negatively impact vaccine uptake among African-American and Afro-Caribbean persons. Interventions to increase the vaccine uptake in the Caribbean must include medical provider and parental involvement. Effective strategies for education and increasing vaccine uptake in BHM are crucial for decreasing cervical cancer burden in the Caribbean