Title: Zn²⁺-Inducible Expression Platform for Synechococcus sp. Strain PCC 7002 Based on the smtA Promoter/Operator and smtB Repressor

Abstract

Synechococcus sp. strain PCC 7002 has been gaining significance as both a model system for photosynthesis research and for industrial applications. Until recently, the genetic toolbox for this model cyanobacterium was rather limited and relied primarily on tools that only allowed constitutive gene expression. This work describes a two-plasmid, Zn²⁺-inducible expression platform that is coupled with a zurA mutation, providing enhanced Zn²⁺uptake. The control elements are based on the metal homeostasis system of a class II metallothionein gene (smtA₇₉₄₂) and its cognate SmtB₇₉₄₂repressor fromSynechococcus elongatusstrain PCC 7942. Under optimal induction conditions, yellow fluorescent protein (YFP) levels were about half of those obtained with the strong, constitutive phycocyanin (cpcBA₆₈₀₃) promoter ofSynechocystissp. strain PCC 6803. This metal-inducible expression system inSynechococcussp. strain PCC 7002 allowed the titratable gene expression of YFP that was up to 19-fold greater than the background level. This system was utilized successfully to control the expression of theDrosophila melanogasterβ-carotene 15,15'-dioxygenase, NinaB, which is toxic when constitutively expressed from a strong promoter inSynechococcussp. strain PCC 7002. Together, these properties establish this metal-inducible system as an additional useful tool that is capable of controlling gene expression for applications ranging from basic research to synthetic biology inSynechococcussp. strain PCC 7002. IMPORTANCEThis ismore » the first metal-responsive expression system in cyanobacteria, to our knowledge, that does not exhibit low sensitivity for induction, which is one of the major hurdles for utilizing this class of genetic tools. In addition, high levels of expression can be generated that approximate those of established constitutive systems, with the added advantage of titratable control. Together, these properties establish this Zn²⁺-inducible system, which is based on thesmtA₇₉₄₂operator/promoter and smtB₇₉₄₂repressor, as a versatile gene expression platform that expands the genetic toolbox ofSynechococcussp. strain PCC 7002.« less

Authors:

Pérez, Adam A. ^[1]; Gajewski, John P. ^[1]; Ferlez, Bryan H. ^[1]; Ludwig, Marcus ^[1]; Baker, Carol S. ^[1]; Golbeck, John H. ^[1]; Bryant, Donald A.  ^[2]

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+ Show Author Affiliations

1. Pennsylvania State Univ., University Park, PA (United States)
2. Pennsylvania State Univ., University Park, PA (United States); Montana State Univ., Bozeman, MT (United States)

Publication Date:

Tue Jan 17 00:00:00 EST 2017

Research Org.:

Pennsylvania State Univ., University Park, PA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1536858

Grant/Contract Number:  

FG02-05ER46222

Resource Type:

Accepted Manuscript

Journal Name:

Applied and Environmental Microbiology

Additional Journal Information:

Journal Volume: 83; Journal Issue: 3; Journal ID: ISSN 0099-2240

Publisher:

American Society for Microbiology

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; Biotechnology & Applied Microbiology; Microbiology