Article

Valine 181 is critical for the nucleotide exchange activity of human mitochondrial ADP/ATP carriers in yeast.

Laboratoire de Physiologie Moléculaire et Cellulaire, IBGC-CNRS, UMR 5095, 1 rue Camille Saint-Saëns, 33077 Bordeaux Cedex, France.
Biochemistry (impact factor: 3.42). 04/2005; 44(11):4342-8. DOI:10.1021/bi0475370 pp.4342-8
Source: PubMed

ABSTRACT We isolated yeast Saccharomyces cerevisiae cells transformed with one of the three human adenine nucleotide carrier genes (HANC) that exhibited higher growth capacity than previously observed. The HANC genes were isolated from these clones, and we identified two independent mutations of HANC that led to replacement of valine 181 located in the fourth transmembrane segment by methionine or phenylalanine. Tolerance of this position toward substitution with various amino acids was systematically investigated, and since HANC/V181M was among the most efficient in growth complementation, it was more extensively studied. Here we show that increased growth capacities were associated with higher ADP/ATP exchange activities and not with higher human carrier amount in yeast mitochondria. These results are discussed in the light of the bovine Ancp structure, that shares more than 90% amino acid identity with Hancps, and its interaction with the lipid environment.

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    Article: Functional expression of human adenine nucleotide translocase 4 in Saccharomyces cerevisiae.
    Takashi Hamazaki, Wai-Yee Leung, Brian D Cain, David A Ostrov, Peter E Thorsness, Naohiro Terada
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    ABSTRACT: The adenine nucleotide translocase (ANT) mediates the exchange of ADP and ATP across the inner mitochondrial membrane. The human genome encodes multiple ANT isoforms that are expressed in a tissue-specific manner. Recently a novel germ cell-specific member of the ANT family, ANT4 (SLC25A31) was identified. Although it is known that targeted depletion of ANT4 in mice resulted in male infertility, the functional biochemical differences between ANT4 and other somatic ANT isoforms remain undetermined. To gain insight into ANT4, we expressed human ANT4 (hANT4) in yeast mitochondria. Unlike the somatic ANT proteins, expression of hANT4 failed to complement an AAC-deficient yeast strain for growth on media requiring mitochondrial respiration. Moreover, overexpression of hANT4 from a multi-copy plasmid interfered with optimal yeast growth. However, mutation of specific amino acids of hANT4 improved yeast mitochondrial expression and supported growth of the AAC-deficient yeast on non-fermentable carbon sources. The mutations affected amino acids predicted to interact with phospholipids, suggesting the importance of lipid interactions for function of this protein. Each mutant hANT4 and the somatic hANTs exhibited similar ADP/ATP exchange kinetics. These data define common and distinct biochemical characteristics of ANT4 in comparison to ANT1, 2 and 3 providing a basis for study of its unique adaptation to germ cells.
    PLoS ONE 01/2011; 6(4):e19250. · 4.09 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

90% amino acid identity
 
bovine Ancp structure
 
efficient
 
exhibited higher growth capacity
 
fourth transmembrane segment
 
growth complementation
 
Hancps
 
higher ADP/ATP exchange activities
 
higher human carrier amount
 
increased growth capacities
 
independent mutations
 
three human adenine nucleotide carrier genes
 
various amino acids
 
yeast mitochondria