Comparative studies of vertebrate endothelin-converting enzyme-like 1 genes and proteins

Roger S Holmes,^1,2 Laura A Cox<sup>1

1</sup>Department of Genetics and Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA; ²Eskitis Institute for Cell and Molecular Therapies and School of Biomolecular and Physical Sciences, Griffith University, Nathan, Queensland, Australia

Abstract: Endothelin-converting enzyme-like 1 (ECEL1) is a member of the M13 family of neutral endopeptidases which play an essential role in the neural regulation of vertebrate respiration. Genetic deficiency of this protein results in respiratory failure soon after birth. Comparative ECEL1 amino acid sequences and structures and ECEL1 gene locations were examined using data from several vertebrate genome projects. Vertebrate ECEL1 sequences shared 66%–99% identity as compared with 30%–63% sequence identities with other M13-like family members, ECE1, ECE2, and NEP (neprilysin or MME). Three N-glycosylation sites were conserved among most vertebrate ECEL1 proteins examined. Sequence alignments, conserved key amino acid residues, and predicted secondary and tertiary structures were also studied, including cytoplasmic, transmembrane, and luminal sequences and active site residues. Vertebrate ECEL1 genes usually contained 18 exons and 17 coding exons on the negative strand. Exons 1 and 2 of the human ECEL1 gene contained 5'-untranslated (5'-UTR) regions, a large CpG island (CpG256), and several transcription factor binding sites which may contribute to the high levels of gene expression previously reported in neural tissues. Phylogenetic analyses examined the relationships and potential evolutionary origins of the vertebrate ECEL1 gene with six other vertebrate neutral endopeptidase M13 family genes. These suggested that ECEL1 originated in an ancestral vertebrate genome from a duplication event in an ancestral neutral endopeptidase M13-like gene.

Keywords: vertebrates, amino acid sequence, ECEL1, ECE1, ECE2, KELL, NEP, NEPL1, PHEX, evolution