Heme regulates the expression in Saccharomyces cerevisiae of chimaeric genes containing 5′-flanking soybean leghemoglobin sequences.

Abstract

The TM1 yeast mutant was transformed with a 2 micron‐derived plasmid (YEp24) which carries a chimaeric gene containing the Escherichia coli chloramphenicol acetyl transferase (CAT) gene fused to the 5′‐ and 3′‐flanking regions of the soybean leghemoglobin (Lb) c3 gene. Expression of the chimaeric CAT gene is controlled specifically by heme at a post‐transcriptional level, most likely by regulating the efficiencies of translation. Expression of another chimaeric gene consisting of the neomycin phosphotransferase (NPTII) gene fused to only the 5′‐flanking region of the Lbc3 gene is regulated by heme in a similar way. Thus, in yeast, heme modulates the translation of the chimaeric mRNAs through interactions with the 5′ Lbc3 non‐coding region.

Interaction of a nodule specific, trans -acting factor with distinct DNA elements in the soybean leghaemoglobin Ibc 3 5′ upstream region

“…To delimit the DNA 1265 ©C IRL Press Limited, Oxford, England (Stougaard et al, 1986). the EcoRI site represents the junction of lbc3 and cat sequences present in plasmid YEpLbCAT (Jensen et al, 1986), which was used as substrate for the subcloning experiments. (B) Retardation gel of the fragments indicated in panel (A), after incubation in the presence of 2 ,ug soybean nodule extract.…”

“…Total protein concentration of the extracts were determined as described by Spector (1978). 1270 trans-acting factor in soybean Ibc3 gene DNA probes for gel retardation studies A DdeI-EcoRI restriction fragment, containing the first 500 bp of the lbc3 5' upstream region was isolated from plasmid YEpLbCAT (Jensen et al, 1986) and digested with the restriction endonucleases indicated in Figure 1A. After repair of the ends of the restriction fragments with the Kienow fragment of DNA polymerase, the blunt ended fragments were subcloned into the filled in BamHI site of pUC 19 (Yanisch-Perron et al, 1985).…”

5′ Analysis of the soybean leghaemoglobin lbc 3 gene: regulatory elements required for promoter activity and organ specificity

“…The pIV2 vector was constructed by subcloning the NOS-NPTII 3'OCS gene (Herrera-Estrella et al, 1983) into the BamHI site of the pIVI plasmid (Stougaard et al, 1987a). pCAT-14 was subsequently constructed by cloning the lbc3 5'3'-CAT gene (Jensen et al, 1986) into the Sall site of pIV2. The 320 bp (PvulAhaIl]) 3'OCS (Gielen et al, 1984) region inserted into the SinaI site of the SP6 polylinker was linked to the CAT coding sequence by cloning the distal 500 bp EcoRI fragment of CAT from Ibc3 5'3'-CATinto the EcoRI polylinker site.…”

A Rhizobium leguminosarum mutant defective in symbiotic iron acquisition

“…Mutant "Fe(III)-anthranilate uptake rates are essential for this conclusion. 282 (10) Although this strain uses diverse sources of complexed iron, only the system defective in 116 is utilized by bac-288 (16) teroids during nodule differentiation, since 116 induces ineffective pea root nodules. Root nodule formation is a lengthy 247 (8) and complex developmental process in which both bacterium and plant cells differentiate in response to mutually 109 (2) (phe-l trp- 16) exchanged chemical signals (29,35 (27,34), the origin of the heme is uncertain.…”

“…282 (10) Although this strain uses diverse sources of complexed iron, only the system defective in 116 is utilized by bac-288 (16) teroids during nodule differentiation, since 116 induces ineffective pea root nodules. Root nodule formation is a lengthy 247 (8) and complex developmental process in which both bacterium and plant cells differentiate in response to mutually 109 (2) (phe-l trp- 16) exchanged chemical signals (29,35 (27,34), the origin of the heme is uncertain. Biochemical (10, lete cells; however, 22), physiological (2,16), and several genetic studies with f R. leguminosarum Hem-mutant strains of root nodule bacteria (19,24) are be due to differing consistent with the microsymbiotic origin of leghemoglobin ptake systems of R.…”