Chapter 10 - Transition Metal Nutrition: A Balance Between Deficiency and Toxicity

Abstract

This chapter describes the known components of the metal homeostasis network in Chlamydomonas, as well as the physiology and the molecular mechanisms of metal tolerance and metal deficiency responses. It delves into the metal tolerance mechanisms in Chlamydomonas and focuses on metal nutrition, deficiency, toxicity and tolerance. Unsuspected biological functions might be unveiled for these metals as more protein structures are elucidated and analytical techniques are improved. The discovery that Cd acts as the metal cofactor of a carbonic anhydrase isoform produced under Zn deficiency in the diatom Thalassiosira weissflogii suggests that metals previously considered to be non-essential and indeed toxic may occasionally act as a prosthetic group in biologically active metalloproteins. Physiological studies, genetic screens and functional analyses of candidate genes have advanced our understanding of the cellular adaptations to metal deficiency or overload in Chlamydomonas. The natural diversity of Chlamydomonas could be exploited to analyze the genetic variation associated with the metal homeostasis network within the species and genus.