Heavy Metal-Associated Isoprenylated Plant Proteins (HIPPs) at Plasmodesmata: Exploring the Link between Localization and Function

Abstract

Heavy metal-associated isoprenylated plant proteins (HIPPs) are a metallochaperone-like protein family comprising a combination of structural features unique to vascular plants. HIPPs possess both one or two heavy metal-binding domains and an isoprenylation site, facilitating a posttranslational protein lipid modification. Recent work has characterized individual HIPPs across numerous different species and provided evidence for varied functionalities. Interestingly, a significant number of HIPPs have been identified in proteomes of plasmodesmata (PD)—nanochannels mediating symplastic connectivity within plant tissues that play pivotal roles in intercellular communication during plant development as well as responses to biotic and abiotic stress. As characterized functions of many HIPPs are linked to stress responses, plasmodesmal HIPP proteins are potentially interesting candidate components of signaling events at or for the regulation of PD. Here, we review what is known about PD-localized HIPP proteins specifically, and how the structure and function of HIPPs more generally could link to known properties and regulation of PD.

The blast effector Pwl2 is a virulence factor that modifies the cellular localisation of host protein HIPP43 to suppress immunity

“…HMA domains are known to be involved in biotic/abiotic stress responses, transport of metals and metal detoxification, and their expression can be organ-specific or tissue-specific within roots, leaves, or stems (40)(41)(42). Moreover, sHMAs can localise to the nucleus, plasma membrane, cytoplasm, or plasmodesmata (41,43,44), suggesting they might be involved in numerous cellular processes. Consistent with this, sHMAs are expanded in plant genomes with more than 45, and more than 50 sHMA domainencoding genes occuring in Arabidopsis and rice respectively (45).…”

Genome-wide characterization of heavy metal-associated isoprenylated plant protein gene family from Citrus sinensis in response to huanglongbing

“…Heavy metal-associated isoprenylated plant proteins (HIPPs) are metal-binding metallochaperones consisting of one or two heavy metal-associated (HMA) domains and an isoprenylation motif ( Barr et al., 2023 ). Moreover, glycine-rich or proline-rich regions are commonly found between the HMA domains and the isoprenylation motif ( Suzuki et al., 2002 ; Barth et al., 2009 ).…”