Poster: Posttranscriptional Regulation
Abs #
1083: A novel cystatin gene is upregulated in pineapple fruit and its product is proteolytically processed by microsomes
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Presenter: |
Neupane, Kabi R., kabi@hawaii.edu | Authors | Neupane, Kabi R. (A) Neuteboom, Leon W. (B) Okazaki, Kristie (B) Christopher, David A. (B) | | Affiliations: |
(A): Leeward Community College, 96-045 Ala Ike St., Pearl City, HI 96782
(B): Department of Molecular Biosciences & Bioengineering, University of Hawaii, 1955 East-West Rd. Honolulu, Hawaii 96822
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Pineapple (Ananas comosus) is a bromeliad CAM plant capable of adapting to drought and heat stress. Very little is known about pineapple genes and their expression during growth. A reverse northern approach was utilized to differentially screen a root-specific cDNA library using tissue-specific probes from root, fruit and aerial tissues. Clones were categorized into 14 classes based on their different tissue-based expression characteristics. 40% of the clones were classified as constitutive, being expressed about equally in all three tissues. Approximately 25% of the clones were expressed higher in roots than the other tissues. A few clones were expressed higher in fruit than any other tissue. One of the fruit-enhanced clones is predicted to encode a cystatin. The expression of the cystatin gene was analyzed in detail in 14 different tissues of a mature plant, as well as in roots and aerial tissue from 3, 6, 13, 20 month-old developing plants and during 5 stages of fruit development. Regardless of tissue and developmental stage analyzed, expression was highest in fruit, particularly the shell. A novel feature of the predicted polypeptide sequence is an unusually long
amino-terminus (75 amino acids) not found in any other cystatin isolated to date. Using in vitro transcription- translation of the cystatin cDNA followed by microsomal processing, we provide evidence that the cystatin is processed by microsomal membranes from 20.7 kDa to 17 kDa, and retains ~40 amino acids of its amino terminus. The potency of the cystatin as an inhibitor of cysteine proteases, such as papain and bromelain, is being determined.
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