Maize phosphoenolpyruvate carboxylase. Cloning and characterization of mRNAs encoding isozymic forms.
The isozymic forms of maize phosphoenolpyruvate carboxylase (P-enolpyruvate carboxylase) involved in photosynthetic CO2 fixation were shown by protein gel blot analysis to consist of 100-kDa subunits. The nonautotrophic isoform found in roots is comprised of 96-kDa subunits and is about 50-100-fold less prevalent. Further analysis of P-enolpyruvate carboxylase isoforms made use of cloned cDNA probes. Two cDNA clones were isolated from a library constructed from maize leaf poly(A) RNA. The largest clone was complementary to about 25% of P-enolpyruvate carboxylase mRNA, which is 3.4 kilobases in length. The quantity of P-enolpyruvate carboxylase mRNA in green, mature leaf tissue was estimated to be 0.20% of poly(A) RNA, whereas P-enolpyruvate carboxylase mRNA in roots was about 100-fold less prevalent. We used thermal denaturation of a P-enolpyruvate carboxylase cDNA probe hybridized to RNA gel blots to estimate the degree of sequence difference between mRNAs encoding different P-enolpyruvate carboxylase isoforms. There appear to be at least two prevalent P-enolpyruvate carboxylase mRNAs in green leaves which are significantly different in sequence, as are P-enolpyruvate carboxylase mRNAs in roots and shoots. The hybridization pattern of maize genomic DNA Southern blots indicates that P-enolpyruvate carboxylase is encoded by a small gene family.
M H
MH
Harpster
W C
WC
Taylor
D002262:Carboxy-Lyases / Q000235:genetics*; D003001:Cloning, Molecular; D007527:Isoenzymes / Q000235:genetics*; D046911:Macromolecular Substances; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics* / Q000302:isolation & purification; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*; D013816:Thermodynamics; D003313:Zea mays / Q000201:enzymology / Q000235:genetics
D007527:Isoenzymes; D046911:Macromolecular Substances; D012333:RNA, Messenger; D002262:Carboxy-Lyases; D010730:Phosphoenolpyruvate Carboxylase