Characterization of Three Photosystem II Mutants in Zea mays L. Lacking a 32,000 Dalton Lamellar Polypeptide

Abstract

Two fully blocked and one partially blocked photosystem II nuclear mutants have been selected in Zea mays. The fully blocked mutants lack photosystem II activity, variable fluorescence, the light-inducible C-550 signal, the high potential form of cytochrome b-559, and most or all of the low potential form of the cytochrome. The block in these mutants may primarily affect the reducing side of photosystem II, inasmuch as chloroplasts isolated from both mutants exhibit an elevated F695 fluorescence emission peak. The partially blocked mutant exhibits partial photosystem 11 activity and a reduction, but not the total loss of the variable fluorescence yield, the C-550 signal, and the high potential form of cytochrome b-559. Lamellae isolated from the fully blocked mutants are greatly deficient for a major lamellar polypeptide with an apparent molecular weight of 32,000 daltons, whereas lamellae from the partially blocked mutant show the partial loss of this same polypeptide, suggesting that the 32,000 dalton polypeptide is necessary for the proper function of photosystem I.Genetic mutants are useful tools for the study of photosynthesis, as has been amply documented in the classic work with algal photosynthetic mutants (22). However, with the exception of the large collection of well characterized pigment mutants in barley (17, 36), the number of photosynthesis mutants studied in any single species of flowering plant has been relatively small. To date, most higher plant photosynthesis mutants are characterized by gross pigment losses which are often accompanied by major alterations in thylakoid membrane morphology and the loss of many lamellar polypeptides (9,15,36,37). Recently, a large collection of photosynthesis mutants was obtained in Zea mays (28) using elevated levels of Chl fluorescence to screen specifically for mutants blocked in photosynthesis (29). By employing this technique, both fully green and yellow-green nuclear mutants with blocks in electron transport, photophosphorylation, and dark reactions have been identified (26,28).The present study describes the characteristics of three nuclear photosynthesis mutants in maize. Two of these mutants, hcf*-33 and hcf*-19G, are fully blocked in PSII, whereas a third mutant, hcf*-19YG, is partially blocked in PSII. All three mutations affect not only PSII activity, but also cause the loss of one or both redox

Release of polypeptides from highly active O2‐evolving photosystem‐2 preparation by this treatment

“…The 33 X 103 M r polypeptide seems also to be similar, in its Mr-value , to that lost in the algal and mayze mutants with deletions in PS-2 [4,5]. A manganese protein isolated fromZea mays [21] hasM r 25 X 103, which is consistent with the 24 X 103Mr protein released by the Tris washing of our PS-2 preparation.…”

“…The enzyme system is so labile that the isolation and characterization of the enzyme complex have not met much success. Several attempts were made to identify the polypeptide(s) involved in the O2-evolution enzyme complex by SDS-PAGE, using plant and algal mutants with deletions in PS-2 [4][5][6]. These results showed a total or partial loss of polypeptides or a change in the electrophoretic mobility of 32-36 × 103 M r polypeptide bands, associated with the mutation.…”

RNA binding and RNA remodeling activities of the half-a-tetratricopeptide (HAT) protein HCF107 underlie its effects on gene expression

“…The Zm-hcf107 mutant was initially detected in the laboratory of Don Miles (University of Missouri, Columbia, MO) as a Mu-transposon-induced mutant lacking photosystem II. Complementation crosses showed this mutant to be allelic to the photosystem II mutant hcf3 (21). Southern blot display of Mu-elements identified a 4.4-kb Hind III fragment harboring a Mu1-element that cosegregated with the mutant phenotype.…”

Nuclear Involvement in the Appearance of a Chloroplast-Encoded 32,000 Dalton Thylakoid Membrane Polypeptide Integral to the Photosystem II Complex

“…We have previously described a series of maize mutants in which the loss of a stainable 32,000 dalton polypeptide was strongly correlated with the specific loss of PSII activity (19). One of these mutants, hcf*-3, is particularly useful for studying specific alterations in PSII because it is fully green, exhibits a full compliment of the major light-harvesting chlorophyll a/b pigment proteins that are associated with the PSII reaction center, and shows minimal losses of lamellar polypeptides other than the stainable 32,000 dalton species (18,19 Stocks segregating hcf*-3 were originally provided by Dr. M. G. Neuffer (Neuffer E-846): subsequent propagation of this accession material, the identification of high fluorescent seedlings, and the conditions under which seedlings were grown for biochemical study have been described previously (18).…”