Nucleotide sequence of a second alpha giardin gene and molecular analysis of the alpha giardin genes and transcripts in Giardia lamblia

• Published in: Molecular and biochemical parasitology Vol. 50; no. 1; pp. 95 - 104
• Main Authors: Alonso, Rogelio A., Peattie, Debra A.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 1992; Elsevier Science
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Blotting, Northern; Blotting, Southern; Cloning, Molecular; Cytoskeletal Proteins - genetics; DNA, Protozoan; Electrophoresis, Gel, Pulsed-Field; Fundamental and applied biological sciences. Psychology; Gene organisation; Genes. Genome; Giardia lamblia; Giardia lamblia - genetics; Giardin; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Protozoan Proteins - genetics; Sequence Alignment; Transcription, Genetic; α-Giardin; Gene organisation; PBS; SDS-PAGE; Giardia lamblia; SSC; SDS; Giardin; α-Giardin; Genetic mapping; Primer extension technique; Protozoa; Nucleotide sequence; Chromosome; Gene organization; In vitro; Characterization; Northern blotting; Proteins; Gene; Giardia intestinalis; Rhizoflagellata; Molecular cloning; Localization; Southern blotting; Pathogen; Aminoacid sequence
• ISSN: 0166-6851; 1872-9428
• DOI: 10.1016/0166-6851(92)90247-H

The giardins are a group of proteins with relative molecular masses ( M rs) between 29 000 and 38 000 that are specific to the ventral disk of the intestinal protozoan parasite Giardia lamblia. We previously have characterized α-giardin, renamed here α-1-giardin, as a novel 33-kDa protein located on the edges of the disk microribbons [5]. Southern blot analysis of G. lamblia genomic DNA, followed by cloning and sequencing, revealed the existence of a related gene that we have called α-2-giardin. Sequence comparison of the α-giardin genes reveals 81% identity at the nucleotide level and 77% at the predicted amino acid level. The predicted α-giardins have similar ( M rs) of approximately 33 900 and are very rich in α-helix conformations. Each gene is present in single copy and, like many other known Giardia coding sequences, exhibits a strong preference for cytidine and guanosine in the third base position of each codon. Chromosome hybridization analysis indicates that both genes are either on the same chromosome or on chromosomes with similar mobility. Experiments utilizing primer extension and RNA sequencing provide evidence that both genes are transcribed. The stable transcripts have extremely short leader regions of only 3 nucleotides, and the downstream sequence of the α-2-giardin gene reveals that the sequence AGTPuAA remains a consistent element within G. lamblia protein-encoding genes.