Molecular cloning, sequencing, predicted amino acid sequence and expression of mammalian valyl-tRNA synthetase

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:5581079

Vilalta, A

Complementary DNA (cDNA) for human valyl-tRNA synthetase (ValRS) is cloned and sequenced as a first step towards understanding the regulation and protein-protein interactions involving ValRS. Several overlapping clones of human cDNA encoding ValRS are isolated. The assembled DNA sequence codes for an open reading frame of 1,051 amino acids with predicted molecular weight of 118 982 and 48.4% identity with S. cerevisiae's ValRS. The deduced amino acid sequence comprises 85% of mammalian ValRS and includes the C-terminus of the enzyme. Several motifs of aminoacyl-tRNA synthetases are conserved in mammalian ValRS. The signature sequences, ATP-binding motif (HIGH) and tRNA 3[prime] end-binding motif (KMSKS) in Class I aminoacyl-tRNA synthetases are conserved. The amino acid binding site (EWCISRQ) is identified at Glu 516. This sequence pattern is conserved in the family of valyl-, isoleucyl- and methionyl-tRNA synthetases. Secondary structure predictions suggest the presence of a highly basic amphiphilic [alpha]-helix between amino acid residues Lys 33 and Lys 50. A similar structure is found at the N-terminus of the yeast ValRS. A newly evolved proteolytic signal PEST sequence (rich in Pro, Glu (Asp), Ser, Thr and flanked by positively charged amino acids) is identified in the human ValRS. The presence of the PEST sequence is consistent with observed protease susceptibility of mammalian ValRS. A 3 kb cDNA fragment of human ValRS is cloned into mammalian expression vector pSVL. This construct is used to transfect COS-7 cells. A 4 to 7 fold increase in ValRS activity is found in transfected cells compared to mock-transfected cells. The high homology to yeast ValRS, the presence of conserved structural motifs, including HIGH, KMSKS and EWCISRQ, and the expression of ValRS activity suggest that the cloned and sequenced cDNA encodes human valyl-tRNA synthetase.

• Research Organization: Georgetown Univ., Washington, DC (United States)
• OSTI ID: 5581079
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
LIGASES
AMINO ACID SEQUENCE
CLONING
DNA SEQUENCING
MAMMALS
GENETICS
GENE REGULATION
MOLECULAR BIOLOGY
MOLECULAR WEIGHT
TRANSFER RNA
ANIMALS
BIOLOGY
ENZYMES
MOLECULAR STRUCTURE
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PROTEINS
RNA
STRUCTURAL CHEMICAL ANALYSIS
VERTEBRATES
550200* - Biochemistry
550400 - Genetics