Comparative Genomics, Illinois

University of Illinois at Urbana-Champaign

Abstracts

Characterization of porcine betaine homocysteine methyltransferase (BHMT) and betaine homocysteine methyltransferase -2 (BHMT2) genes

Radhika S. Ganu , Timothy A. Garrow, Monika Sodhi3 , Lawrence B. Schook

Abstract

Betaine homocysteine methyltransferase (BHMT) and BHMT-2 methylate homocysteine using betaine or S-methylmethionine, respectively.  These enzyme activities are found only in the liver of adult rodents, but in the liver and kidney of adult humans and pigs. Using a pig model, we seek to understand the developmental expression pattern of these enzymes in different porcine organs. Immunohistochemical staining revealed the presence of BHMT in adult liver and kidney cortex, as reported earlier, and also in fetal lungs (aged days 30, 60, 84, 90, 105). Full length cDNA of BHMT and BHMT-2 were cloned and sequenced, and the 5’ and 3’ UTRs were amplified using RLM-RACE. BHMT has a longer 5’ and 3’ UTR, consisting of 77 and 1142 nucleotides, whereas BHMT-2 consisted of 17 and 893 nucleotides respectively. The predicted primary sequences of BHMT and BHMT-2 contain 407 and 363 amino acids, respectively, and share 78% amino acid identity. Relative to BHMT-2, BHMT has two additional regions of amino acid sequence; a 9 amino acid sequence (86-94) in the N-terminal region, and 34 amino acid sequence (373-407) at the carboxy terminus. Preliminary sequencing results identified two isoforms of liver BHMT gene resulting from alternative splicing of 5’ UTR. BHMT enzymes are organ/developmental stage-dependent and further sequence analysis might reveal new splice variants that result in different protein functions.