Molecular analysis of two cDNA clones encoding acidic class I chitinase in Maize

The cloning and analysis of two different cDNA clones encoding putative maize (Zea mays 1.) chitinases obtained by polymerase chain reaction (PCR) and cDNA library screening i s described. The cDNA library was made from poly(A)+ RNA from leaves challenged with mercuric chloride for 2 d. l h e two clones, pCh2 and pCh11, appear to encode class I chitinase isoforms with cysteine-rich domains (not found in pChl1 due to the incomplete sequence) and proline-lglycine-rich or proline-rich hinge domains, respedively. l h e pCh11 clone resembles a previously reported maize seed chitinase; however, the deduced proteins were found to have acidic isoeledric points. Analysis of all monocot chitinase sequences available to date shows that not all class I chitinases possess the basic isoelectric points usually found in dicotyledonous plants and that monocot class II chitinases do not necessarily exhibit acidic isoelectric points. Based on sequence analysis, the pCh2 protein i