Dr Steven Hussey



Senior Lecturer

Department

Biochemistry, Genetics and Microbiology
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Research Profiles

My Files

All of biology is transcriptionally wired. The regulation of secondary cell wall biosynthesis during wood formation in trees such as Eucalyptus is no exception.  Previous studies, mostly in Arabidopsis and Populus, have deciphered a highly ramified transcriptional network hierarchically regulating secondary cell wall biosynthesis (Figure 1). Many of these transcription factors remain to be functionally characterized and their direct and indirect targets identified.

My group uses transcriptome data, DAP-seq, transgenesis, protoplast transfection, bioinformatics and chromatin immunoprecipitation sequencing (ChIP-seq) to functionally characterize key Eucalyptus transcription factors.  Particularly, we are exploring the most recent high-throughput techniques for rapid and informative reconstruction of secondary cell wall transcriptional networks in non-model organisms. We are also interested in understanding the role of chromatin architecture in shaping transcriptional responses and their differences between tissues. In addition to understanding the fundamental biology of wood formation and how it is transcriptionally and epigenetically regulated, we hope to enhance economically important woody traits through manipulation of transcription factors regulating particular aspects of wood formation.

 

Hussey group 2018. From left to right, top: Ms Katrien Brown (MSc student), Dr Steven Hussey, Ms Lungile Mabuza (MSc student), Mr Lazarus Takawira (PhD student). Bottom: Ms Michaela Smit (BSc Hons), Ms Ipeleng Randome (PhD student), Dr Raphael Ployet (postdoc).

 

Synthetic biology

The ability to re-engineer biological systems such as biochemical pathways or transcriptional networks is a hallmark of synthetic biology. We are starting to develop synthetic biology applications in forest trees, beginning with the design and chemical synthesis of 221 E. grandis secondary cell wall-related transcription factors and 65 promoters as standardized, domesticated Phytobricks that can be used for GoldenGate, MoClo and GoldenBraid 2.0 assembly. This work is part of a community DNA synthesis grant awarded by the DOE-JGI, and the synthetic panel will be freely available to the international community (see FMG's synthetic biology page).

 

Figure 1. Design of standardized synthetic E. grandis SCW-related transcription factors and promoters. Hammers indicate domesticated sequences, dotted lines indicate restriction cleavage sites, coloured bases indicate standard syntax sequences and lowercase sequences indicate spacer nucleotides. (A) Transcription factor Phytobricks contain attL GATEWAY recombination sites (green), fifty-one basepair chewback linkers, BsaI Type IIS recognition sites and standard syntax sequences (purple text). The start codon of the domesticated coding sequence (green) remains in frame with N-terminal tags in GATEWAY destination vectors, while being primarily intended for Golden Gate, MoClo and Golden Braid assembly. (B) The DNA Affinity Purification Sequencing (DAP-seq) panel of transcription factors is available as a C-terminal fusion to the HALO purification tag, intended for in vitro transcription and translation via the SP6 phage promoter. While not standardized by a universal syntax, the coding sequences are fully domesticated and can thus be subcloned as standardized parts into a universal acceptor plasmid. (C) The secondary cell wall promoter panel features semi-domesticated 2 kb promoter sequences (including 5’ UTRs) compatible with GATEWAY and AarI-mediated Golden Gate cloning. Standard prefix and suffix syntax sequences allow for two-step Type IIS assembly to any Phytobrick panel CDS in (A). AmpR, ampicillin resistance gene; CDS, coding sequence; SpecR, spectinomycin resistance gene.

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Book Chapters
Hussey SG, Wegrzyn JL, Vasquez-Gross HA. 2016. Evolutionary Histories of Gene Families in Angiosperm Trees. In: Comparative and Evolutionary Genomics of Angiosperm Trees. Groover A, Cronk Q. (eds). Springer International Publishing, Cham, pp 1-17.
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Publication
Laubscher M, Brown K, Tonfack LB, Myburg AA, Mizrachi E, Hussey SG. (2018) Temporal analysis of Arabidopsis genes activated by Eucalyptus grandis NAC transcription factors associated with xylem fibre and vessel development. Scientific Reports 8:10983. 10.1038/s41598-018-29278-w
Lu Q, Shao F, Macmillan C, Wilson IW, van der Merwe K, Hussey SG, Myburg AA, Dong X, Qiu D. (2018) Genomewide analysis of the lateral organ boundaries domain (LBD) gene family in Eucalyptus grandis reveals members that differentially impact secondary growth. Plant Biotechnology Journal 10.1111/pbi.12754
Hussey SG, Loots MT, van der Merwe K, Mizrachi E, Myburg AA. (2017) Integrated analysis and transcript abundance modelling of H3K4me3 and H3K27me3 in developing secondary xylem. Scientific Reports 7:3370. 10.1038/s41598-017-03665-1
Hussey SG, Mizrachi E, Groover A, Berger DK, Myburg AA. (2015) Genome-wide mapping of histone H3 lysine 4 trimethylation in Eucalyptus grandis developing xylem. BMC Plant Biology 15:117. 10.1186/s12870-015-0499-0 PDF
Hussey SG, Saïdi MN, Hefer C, Myburg AA, Grima-Pettenati J. (2014) Structural, evolutionary and functional analysis of the NAC domain protein family in Eucalyptus. New Phytologist 206(4):1337-1350. 10.1111/nph.13139
Myburg AA, Grattapaglia D, Tuskan GA, Hellsten U, Hayes RD, Grimwood J, Jenkins J, Lindquist E, Tice H, Bauer D, Goodstein DM, Dubchak I, Poliakov A, Mizrachi E, Kullan ARK, Hussey SG, Pinard D, Van der Merwe K, Singh P, et al. (2014) The genome of Eucalyptus grandis. Nature 510:356-362. 10.1038/nature13308
Hussey SG, Mizrachi E, Creux NM, Myburg AA. (2013) Navigating the transcriptional roadmap regulating plant secondary cell wall deposition. Frontiers in Plant Science 4(325):1-21. 10.3389/fpls.2013.00325
Hussey SG, Mizrachi E, Spokevicius AV, Bossinger G, Berger DK. (2011) SND2, a NAC transcription factor gene, regulates genes involved in secondary cell wall development in Arabidopsis fibres and increases fibre cell area in Eucalyptus. BMC Plant Biology 11:173. 10.1186/1471-2229-11-173
Botha J, Pinard D, Creux N, Hussey S, Maritz-Olivier C, Spokevicius A, Bossinger G, Mizrachi E, Myburg AA. (2011) Characterising the role of the Eucalyptus grandis SND2 promoter in secondary cell wall biosynthesis. BMC Proceedings 5(7):P105. 10.1186/1753-6561-5-S7-P105
Hussey S, Mizrachi E, Berger D, Myburg AA. (2011) The role of SND2 in the regulation of Arabidopsis fibre secondary cell wall formation. BMC Proceedings 5(7):P114. 10.1186/1753-6561-5-S7-P114