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A chenopod extensin lacks repetitive tetrahydroxyproline blocks
X B Li1, M Kieliszewski, D T Lamport
1D.O.E. Plant Research Laboratory and Department of Biochemistry, Michigan State University, East Lansing, Michigan 48824.
Plant Physiology
|February 1, 1990
Summary
Researchers identified a novel extensin in sugar beet cell cultures. This protein, while lacking a typical extensin feature, shares structural similarities with tomato extensin, suggesting a broader definition for this plant cell wall protein family.
Area of Science:
- Plant Molecular Biology
- Biochemistry
- Cell Biology
Background:
- Extensins are essential structural glycoproteins in plant cell walls.
- A characteristic feature of extensins is the Ser-Hyp-Hyp-Hyp-Hyp pentameric motif.
- Previous research has focused on the conserved nature of extensin structure.
Purpose of the Study:
- To characterize a novel extensin isolated from sugar beet (Beta vulgaris) cell suspension cultures.
- To investigate the structural similarities and differences between sugar beet extensin and other known extensins.
- To re-evaluate the classification of certain repetitive cDNA sequences based on extensin structural motifs.
Main Methods:
- Isolation and purification of extensin from sugar beet cell suspension cultures.
- Tryptic peptide analysis and sequencing.
- Sequence comparison with known extensins, including tomato extensin P1, soybean nodulin N75, and carrot wound-induced P33.
Main Results:
- Sugar beet extensin lacks the diagnostic Ser-Hyp-Hyp-Hyp-Hyp pentamer.
- Sequence analysis revealed a shared motif with tomato extensin P1, but with a split tetra(hydroxy)proline block due to an insertion sequence [X].
- Three highly repetitive cDNA sequences, including soybean nodulin N75 and carrot P33, were reinterpreted as extensins with split tetra(hydroxy)proline blocks.
Conclusions:
- The definition of extensins may need to be broadened to include proteins with split tetra(hydroxy)proline blocks.
- Structural variations in extensins, such as insertion sequences, contribute to their diversity.
- This study provides new insights into the classification and evolution of plant cell wall proteins.