title: The solution structure and heme binding of the presequence of murine 5-aminolevulinate synthase.
abstract: The mitochondrial import of 5-aminolevulinate synthase (ALAS), the first enzyme of the mammalian heme biosynthetic pathway, requires the N-terminal presequence. The 49 amino acid presequence transit peptide (psALAS) for murine erythroid ALAS was chemically synthesized, and circular dichroism and (1)H nuclear magnetic resonance (NMR) spectroscopies used to determine structural elements in trifluoroethanol/H(2)O solutions and micellar environments. A well defined amphipathic alpha-helix, spanning L22 to F33, was present in psALAS in 50% trifluoroethanol. Further, a short alpha-helix, defined by A5-L8, was also apparent in the 26 amino acid N-terminus peptide, when its structure was determined in sodium dodecyl sulfate. Heme inhibition of ALAS mitochondrial import has been reported to be mediated through cysteine residues in presequence heme regulatory motifs (HRMs). A UV/visible and (1)H NMR study of hemin and psALAS indicated that a heme-peptide interaction occurs and demonstrates, for the first time, that heme interacts with the HRMs of psALAS.
authors.affiliation: Departamento de Quimica, Universidade de Aveiro, 3810-193 Aviero, Portugal.
authors.forename: B J
authors.initials: BJ
authors.lastname: Goodfellow
authors.forename: J S
authors.initials: JS
authors.lastname: Dias
authors.forename: G C
authors.initials: GC
authors.lastname: Ferreira
authors.forename: P
authors.initials: P
authors.lastname: Henklein
authors.forename: V
authors.initials: V
authors.lastname: Wray
authors.forename: A L
authors.initials: AL
authors.lastname: Macedo
mesh_terms: D000624:5-Aminolevulinate Synthetase / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D002942:Circular Dichroism; D006418:Heme / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013053:Spectrophotometry
chemical_list: D000596:Amino Acids; D010455:Peptides; D006418:Heme; D000624:5-Aminolevulinate Synthetase