Manganese is an essential trace nutrient for organisms, because of its role in cofactoring enzymes and providing protection against reactive oxygen species (ROS). Many bacteria require manganese to form pathogenic or symbiotic interactions with eukaryotic host cells. However, excess manganese is toxic, requiring cells to have manganese export mechanisms. Bacteria are currently known to possess two widely-distributed classes of manganese export proteins, MntP and MntE, but other types of transporters likely exist. Moreover, the structure and function of MntP is not well understood. Here, we characterized the role of three structurally related proteins known or predicted to be involved in manganese transport in bacteria from the MntP, UPF0016 and TerC families. These studies used computational analysis to analyze phylogeny and structure, physiological assays to test sensitivity to high levels of manganese and ROS, and ICP-MS to measure metal levels. We found that MntP alters cellular resistance to ROS. Moreover, we used extensive computational analyses and phenotypic assays to identify amino acids required for MntP activity. These negativelycharged residues likely serve to directly bind manganese and transport it from the cytoplasm through the membrane. We further characterized two other potential manganese transporters associated with a Mn-sensing riboswitch, and found that the UPF0016 family of proteins has manganese export activity. We provide the first phenotypic and biochemical evidence for the role of Alx, a member of the TerC family, in manganese homeostasis. It does not appear to export manganese, rather it intriguingly facilitates an increase in intracellular manganese concentration. These findings expand knowledge about the identity and mechanisms of manganese homeostasis proteins across bacteria and show that proximity to a Mnresponsive riboswitch can be used to identify new components of the manganese homeostasis machinery. INTRODUCTIONTransition metals are essential for life as they play important roles as enzyme cofactors and structural components of proteins and RNAs. Reflecting this, one third of the proteomes of organisms from bacteria to humans consist of metalloproteins (1,2). In bacteria, metal availability is intimately involved in pathogenesis. Bacteria unable to maintain proper metal homeostasis are less virulent, and mammalian hosts actively seek to withhold essential metals from invading bacteria (3,4). Yet in excess, metals are toxic to cells. This toxicity typically results from metaldependent oxidative damage (e.g., the Fenton reaction) and/or the displacement of cognate metals from their binding sites by the metal that is in excess (3,(5)(6)(7)(8). Thus, cells have a battery of metal importers, exporters, sequestration factors, and regulators to carefully control the intracellular level of each metal (1,2,9,10).

Highlights d PIM1 is highly expressed in suppressive neutrophils during chronic viral infection d PIM1 promotes mitochondrial fitness and cell survival in suppressive neutrophils d PIM kinase inhibition diminishes suppressive neutrophilmediated immunosuppression

To address the water mark issue from hydrophobic film drying, and the stringent particle removal requirements for the 45nm technology node and beyond, we developed a cleaner with an innovative single wafer Marangoni dryer. The single wafer Marangoni dryer design features and process characterization data are presented in this paper. The major results can be summarized as: (1) With the immersion type Marangoni dryer, as the wafer is lifted out of a DIW bath, a stable and uniform meniscus can be easily maintained, making the single-wafer Marangoni dryer ideal for drying hydrophilic, hydrophobic or hydrophobic/hydrophilic mixed patterned wafers; (2) The new Marangoni dryer leaves ~14nm [1] water film on the wafer after drying, therefore any dissolved or suspended materials contained inside the water film, and potentially left on the wafer surface after water evaporation, is less than 14nm in diameter. This feature is critical for the 45nm technology node and beyond because 23nm particle could be killer defects at these nodes [2]; (3) Because of the strong Marangoni flow effect, high aspect ratio features can be completely dried without leaving any water droplets inside the trenches; therefore copper corrosion can be prevented; (4) The Marangoni dryer uses N2 as the carrier gas, so when a wafer is lifted out of the degasified DIW bath through the N2/IPA spray zone, it is thoroughly dried in an oxygen-free environment before exposure to the ambient environment; (5) The Marangoni dryer is free of electrostatic charge and centrifugal force because of the slow (2mm/s~20mm/s) wafer linear lifting speed compared to linear speed at wafer edge during SRD.

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