Search bioRxiv⌕ Search

Biology subjects

Lepper, A.

Publications and source records attributed to Lepper, A..

2 recordsLinked to original sources

A GreenGate-compatible vector set for efficient protein purification from E. coli

Recombinant protein purification from E. coli frequently requires screening various affinity tags and variations to optimize yield and purity. However, classical cloning methods are limited in throughput and modularity, which is circumvented by GoldenGate cloning. While GreenGate cloning, a GoldenGate variant, is widely used in plant research, it lacks compatibility with E. coli expression vectors. Here, we introduce a comprehensive, GreenGate-compatible vector toolkit for efficient and versatile assembly of three modules, for N- and C-terminal tagging of a protein of interest into an IPTG-inducible E. coli expression vector. To allow versatility, this toolkit contains diverse affinity tags, with or without HRV3C protease cleavage sites. Moreover, we included plasmids for the homemade low-cost production of this protease. This GreenGate-compatible toolkit allows efficient combinations of different tags and eliminates the need for re-cloning modules between plant and bacterial systems, streamlining the workflow for recombinant protein production, especially in plant research.

Plant Biology↗

Polarised subcellular activation of ROPs by specific ROPGEFs drives pollen germination in Arabidopsis thaliana

During plant fertilisation, excess male gametes compete for a limited number of female gametes. The dormant male gametophyte, encapsulated in the pollen grain, consists of two sperm cells enclosed in a vegetative cell. After reaching the stigma of a compatible flower, quick and efficient germination of the vegetative cell to a tip-growing pollen tube is crucial to ensure fertilisation success. RHO OF PLANTS (ROP) signalling and their activating ROP GUANINE NUCLEOTIDE EXCHANGE FACTORS (ROPGEFs) are essential for initiating polar growth processes in multiple cell types. However, which ROPGEFs activate pollen germination is unknown. We investigated the role of ROPGEFs in initiating pollen germination and the required cell polarity establishment. Of the five pollen-expressed ROPGEFs, we found that GEF8, GEF9, and GEF12 are required for pollen germination and male fertilisation success, as gef8;gef9;gef12 triple mutants showed almost complete loss of pollen germination in vitro and had a reduced allele transmission rate. Live cell imaging and spatiotemporal analysis of subcellular protein distribution showed that GEF8 and GEF9, but not GEF12, displayed transient polar protein accumulations at the future site of pollen germination minutes before pollen germination, demonstrating specific roles for GEF8 and GEF9 during the initiation of pollen germination. Furthermore, this novel GEF accumulation appears in a biphasic temporal manner and can shift its location. We showed that the C-terminal domain of GEF8 and GEF9 confers this protein accumulation and demonstrated that GEFs locally activate ROPs and alter Ca2+ signalling, which is required for pollen tube germination. We demonstrated that GEFs do not act redundantly during pollen germination and described for the first time a polar domain with spatiotemporal flexibility, which is crucial for the de novo establishment of a polar growth domain within a cell and, thus, for pollen function and fertilisation success.

plant biology↗